Once again Tavas started eating coffee mix without water! Keione told him that it smells awful, but he didn't stop doing that. That's why Keione told his smart friend, SaDDas to punish him! SaDDas took Tavas' headphones and told him: "If you solve the following problem, I'll return it to you."

<image>

The problem is: 

You are given a lucky number n. Lucky numbers are the positive integers whose decimal representations contain only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.

If we sort all lucky numbers in increasing order, what's the 1-based index of n? 

Tavas is not as smart as SaDDas, so he asked you to do him a favor and solve this problem so he can have his headphones back.

Input

The first and only line of input contains a lucky number n (1 ≤ n ≤ 109).

Output

Print the index of n among all lucky numbers.

Examples

Input

4


Output

1


Input

7


Output

2


Input

77


Output

6

import java.io.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class Gots {

    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter writer = new PrintWriter(System.out);
        List<Integer> l = new ArrayList();
        String[] input = reader.readLine().split(" ");
        int N = Integer.parseInt(input[0]);
        int[] a = {
            4,
            7,
            44,
            47,
            74,
            77,
            444,
            447,
            474,
            477,
            744,
            747,
            774,
            777,
            4444,
            4447,
            4474,
            4477,
            4744,
            4747,
            4774,
            4777,
            7444,
            7447,
            7474,
            7477,
            7744,
            7747,
            7774,
            7777,
            44444,
            44447,
            44474,
            44477,
            44744,
            44747,
            44774,
            44777,
            47444,
            47447,
            47474,
            47477,
            47744,
            47747,
            47774,
            47777,
            74444,
            74447,
            74474,
            74477,
            74744,
            74747,
            74774,
            74777,
            77444,
            77447,
            77474,
            77477,
            77744,
            77747,
            77774,
            77777,
            444444,
            444447,
            444474,
            444477,
            444744,
            444747,
            444774,
            444777,
            447444,
            447447,
            447474,
            447477,
            447744,
            447747,
            447774,
            447777,
            474444,
            474447,
            474474,
            474477,
            474744,
            474747,
            474774,
            474777,
            477444,
            477447,
            477474,
            477477,
            477744,
            477747,
            477774,
            477777,
            744444,
            744447,
            744474,
            744477,
            744744,
            744747,
            744774,
            744777,
            747444,
            747447,
            747474,
            747477,
            747744,
            747747,
            747774,
            747777,
            774444,
            774447,
            774474,
            774477,
            774744,
            774747,
            774774,
            774777,
            777444,
            777447,
            777474,
            777477,
            777744,
            777747,
            777774,
            777777,
            4444444,
            4444447,
            4444474,
            4444477,
            4444744,
            4444747,
            4444774,
            4444777,
            4447444,
            4447447,
            4447474,
            4447477,
            4447744,
            4447747,
            4447774,
            4447777,
            4474444,
            4474447,
            4474474,
            4474477,
            4474744,
            4474747,
            4474774,
            4474777,
            4477444,
            4477447,
            4477474,
            4477477,
            4477744,
            4477747,
            4477774,
            4477777,
            4744444,
            4744447,
            4744474,
            4744477,
            4744744,
            4744747,
            4744774,
            4744777,
            4747444,
            4747447,
            4747474,
            4747477,
            4747744,
            4747747,
            4747774,
            4747777,
            4774444,
            4774447,
            4774474,
            4774477,
            4774744,
            4774747,
            4774774,
            4774777,
            4777444,
            4777447,
            4777474,
            4777477,
            4777744,
            4777747,
            4777774,
            4777777,
            7444444,
            7444447,
            7444474,
            7444477,
            7444744,
            7444747,
            7444774,
            7444777,
            7447444,
            7447447,
            7447474,
            7447477,
            7447744,
            7447747,
            7447774,
            7447777,
            7474444,
            7474447,
            7474474,
            7474477,
            7474744,
            7474747,
            7474774,
            7474777,
            7477444,
            7477447,
            7477474,
            7477477,
            7477744,
            7477747,
            7477774,
            7477777,
            7744444,
            7744447,
            7744474,
            7744477,
            7744744,
            7744747,
            7744774,
            7744777,
            7747444,
            7747447,
            7747474,
            7747477,
            7747744,
            7747747,
            7747774,
            7747777,
            7774444,
            7774447,
            7774474,
            7774477,
            7774744,
            7774747,
            7774774,
            7774777,
            7777444,
            7777447,
            7777474,
            7777477,
            7777744,
            7777747,
            7777774,
            7777777,
            44444444,
            44444447,
            44444474,
            44444477,
            44444744,
            44444747,
            44444774,
            44444777,
            44447444,
            44447447,
            44447474,
            44447477,
            44447744,
            44447747,
            44447774,
            44447777,
            44474444,
            44474447,
            44474474,
            44474477,
            44474744,
            44474747,
            44474774,
            44474777,
            44477444,
            44477447,
            44477474,
            44477477,
            44477744,
            44477747,
            44477774,
            44477777,
            44744444,
            44744447,
            44744474,
            44744477,
            44744744,
            44744747,
            44744774,
            44744777,
            44747444,
            44747447,
            44747474,
            44747477,
            44747744,
            44747747,
            44747774,
            44747777,
            44774444,
            44774447,
            44774474,
            44774477,
            44774744,
            44774747,
            44774774,
            44774777,
            44777444,
            44777447,
            44777474,
            44777477,
            44777744,
            44777747,
            44777774,
            44777777,
            47444444,
            47444447,
            47444474,
            47444477,
            47444744,
            47444747,
            47444774,
            47444777,
            47447444,
            47447447,
            47447474,
            47447477,
            47447744,
            47447747,
            47447774,
            47447777,
            47474444,
            47474447,
            47474474,
            47474477,
            47474744,
            47474747,
            47474774,
            47474777,
            47477444,
            47477447,
            47477474,
            47477477,
            47477744,
            47477747,
            47477774,
            47477777,
            47744444,
            47744447,
            47744474,
            47744477,
            47744744,
            47744747,
            47744774,
            47744777,
            47747444,
            47747447,
            47747474,
            47747477,
            47747744,
            47747747,
            47747774,
            47747777,
            47774444,
            47774447,
            47774474,
            47774477,
            47774744,
            47774747,
            47774774,
            47774777,
            47777444,
            47777447,
            47777474,
            47777477,
            47777744,
            47777747,
            47777774,
            47777777,
            74444444,
            74444447,
            74444474,
            74444477,
            74444744,
            74444747,
            74444774,
            74444777,
            74447444,
            74447447,
            74447474,
            74447477,
            74447744,
            74447747,
            74447774,
            74447777,
            74474444,
            74474447,
            74474474,
            74474477,
            74474744,
            74474747,
            74474774,
            74474777,
            74477444,
            74477447,
            74477474,
            74477477,
            74477744,
            74477747,
            74477774,
            74477777,
            74744444,
            74744447,
            74744474,
            74744477,
            74744744,
            74744747,
            74744774,
            74744777,
            74747444,
            74747447,
            74747474,
            74747477,
            74747744,
            74747747,
            74747774,
            74747777,
            74774444,
            74774447,
            74774474,
            74774477,
            74774744,
            74774747,
            74774774,
            74774777,
            74777444,
            74777447,
            74777474,
            74777477,
            74777744,
            74777747,
            74777774,
            74777777,
            77444444,
            77444447,
            77444474,
            77444477,
            77444744,
            77444747,
            77444774,
            77444777,
            77447444,
            77447447,
            77447474,
            77447477,
            77447744,
            77447747,
            77447774,
            77447777,
            77474444,
            77474447,
            77474474,
            77474477,
            77474744,
            77474747,
            77474774,
            77474777,
            77477444,
            77477447,
            77477474,
            77477477,
            77477744,
            77477747,
            77477774,
            77477777,
            77744444,
            77744447,
            77744474,
            77744477,
            77744744,
            77744747,
            77744774,
            77744777,
            77747444,
            77747447,
            77747474,
            77747477,
            77747744,
            77747747,
            77747774,
            77747777,
            77774444,
            77774447,
            77774474,
            77774477,
            77774744,
            77774747,
            77774774,
            77774777,
            77777444,
            77777447,
            77777474,
            77777477,
            77777744,
            77777747,
            77777774,
            77777777,
            444444444,
            444444447,
            444444474,
            444444477,
            444444744,
            444444747,
            444444774,
            444444777,
            444447444,
            444447447,
            444447474,
            444447477,
            444447744,
            444447747,
            444447774,
            444447777,
            444474444,
            444474447,
            444474474,
            444474477,
            444474744,
            444474747,
            444474774,
            444474777,
            444477444,
            444477447,
            444477474,
            444477477,
            444477744,
            444477747,
            444477774,
            444477777,
            444744444,
            444744447,
            444744474,
            444744477,
            444744744,
            444744747,
            444744774,
            444744777,
            444747444,
            444747447,
            444747474,
            444747477,
            444747744,
            444747747,
            444747774,
            444747777,
            444774444,
            444774447,
            444774474,
            444774477,
            444774744,
            444774747,
            444774774,
            444774777,
            444777444,
            444777447,
            444777474,
            444777477,
            444777744,
            444777747,
            444777774,
            444777777,
            447444444,
            447444447,
            447444474,
            447444477,
            447444744,
            447444747,
            447444774,
            447444777,
            447447444,
            447447447,
            447447474,
            447447477,
            447447744,
            447447747,
            447447774,
            447447777,
            447474444,
            447474447,
            447474474,
            447474477,
            447474744,
            447474747,
            447474774,
            447474777,
            447477444,
            447477447,
            447477474,
            447477477,
            447477744,
            447477747,
            447477774,
            447477777,
            447744444,
            447744447,
            447744474,
            447744477,
            447744744,
            447744747,
            447744774,
            447744777,
            447747444,
            447747447,
            447747474,
            447747477,
            447747744,
            447747747,
            447747774,
            447747777,
            447774444,
            447774447,
            447774474,
            447774477,
            447774744,
            447774747,
            447774774,
            447774777,
            447777444,
            447777447,
            447777474,
            447777477,
            447777744,
            447777747,
            447777774,
            447777777,
            474444444,
            474444447,
            474444474,
            474444477,
            474444744,
            474444747,
            474444774,
            474444777,
            474447444,
            474447447,
            474447474,
            474447477,
            474447744,
            474447747,
            474447774,
            474447777,
            474474444,
            474474447,
            474474474,
            474474477,
            474474744,
            474474747,
            474474774,
            474474777,
            474477444,
            474477447,
            474477474,
            474477477,
            474477744,
            474477747,
            474477774,
            474477777,
            474744444,
            474744447,
            474744474,
            474744477,
            474744744,
            474744747,
            474744774,
            474744777,
            474747444,
            474747447,
            474747474,
            474747477,
            474747744,
            474747747,
            474747774,
            474747777,
            474774444,
            474774447,
            474774474,
            474774477,
            474774744,
            474774747,
            474774774,
            474774777,
            474777444,
            474777447,
            474777474,
            474777477,
            474777744,
            474777747,
            474777774,
            474777777,
            477444444,
            477444447,
            477444474,
            477444477,
            477444744,
            477444747,
            477444774,
            477444777,
            477447444,
            477447447,
            477447474,
            477447477,
            477447744,
            477447747,
            477447774,
            477447777,
            477474444,
            477474447,
            477474474,
            477474477,
            477474744,
            477474747,
            477474774,
            477474777,
            477477444,
            477477447,
            477477474,
            477477477,
            477477744,
            477477747,
            477477774,
            477477777,
            477744444,
            477744447,
            477744474,
            477744477,
            477744744,
            477744747,
            477744774,
            477744777,
            477747444,
            477747447,
            477747474,
            477747477,
            477747744,
            477747747,
            477747774,
            477747777,
            477774444,
            477774447,
            477774474,
            477774477,
            477774744,
            477774747,
            477774774,
            477774777,
            477777444,
            477777447,
            477777474,
            477777477,
            477777744,
            477777747,
            477777774,
            477777777,
            744444444,
            744444447,
            744444474,
            744444477,
            744444744,
            744444747,
            744444774,
            744444777,
            744447444,
            744447447,
            744447474,
            744447477,
            744447744,
            744447747,
            744447774,
            744447777,
            744474444,
            744474447,
            744474474,
            744474477,
            744474744,
            744474747,
            744474774,
            744474777,
            744477444,
            744477447,
            744477474,
            744477477,
            744477744,
            744477747,
            744477774,
            744477777,
            744744444,
            744744447,
            744744474,
            744744477,
            744744744,
            744744747,
            744744774,
            744744777,
            744747444,
            744747447,
            744747474,
            744747477,
            744747744,
            744747747,
            744747774,
            744747777,
            744774444,
            744774447,
            744774474,
            744774477,
            744774744,
            744774747,
            744774774,
            744774777,
            744777444,
            744777447,
            744777474,
            744777477,
            744777744,
            744777747,
            744777774,
            744777777,
            747444444,
            747444447,
            747444474,
            747444477,
            747444744,
            747444747,
            747444774,
            747444777,
            747447444,
            747447447,
            747447474,
            747447477,
            747447744,
            747447747,
            747447774,
            747447777,
            747474444,
            747474447,
            747474474,
            747474477,
            747474744,
            747474747,
            747474774,
            747474777,
            747477444,
            747477447,
            747477474,
            747477477,
            747477744,
            747477747,
            747477774,
            747477777,
            747744444,
            747744447,
            747744474,
            747744477,
            747744744,
            747744747,
            747744774,
            747744777,
            747747444,
            747747447,
            747747474,
            747747477,
            747747744,
            747747747,
            747747774,
            747747777,
            747774444,
            747774447,
            747774474,
            747774477,
            747774744,
            747774747,
            747774774,
            747774777,
            747777444,
            747777447,
            747777474,
            747777477,
            747777744,
            747777747,
            747777774,
            747777777,
            774444444,
            774444447,
            774444474,
            774444477,
            774444744,
            774444747,
            774444774,
            774444777,
            774447444,
            774447447,
            774447474,
            774447477,
            774447744,
            774447747,
            774447774,
            774447777,
            774474444,
            774474447,
            774474474,
            774474477,
            774474744,
            774474747,
            774474774,
            774474777,
            774477444,
            774477447,
            774477474,
            774477477,
            774477744,
            774477747,
            774477774,
            774477777,
            774744444,
            774744447,
            774744474,
            774744477,
            774744744,
            774744747,
            774744774,
            774744777,
            774747444,
            774747447,
            774747474,
            774747477,
            774747744,
            774747747,
            774747774,
            774747777,
            774774444,
            774774447,
            774774474,
            774774477,
            774774744,
            774774747,
            774774774,
            774774777,
            774777444,
            774777447,
            774777474,
            774777477,
            774777744,
            774777747,
            774777774,
            774777777,
            777444444,
            777444447,
            777444474,
            777444477,
            777444744,
            777444747,
            777444774,
            777444777,
            777447444,
            777447447,
            777447474,
            777447477,
            777447744,
            777447747,
            777447774,
            777447777,
            777474444,
            777474447,
            777474474,
            777474477,
            777474744,
            777474747,
            777474774,
            777474777,
            777477444,
            777477447,
            777477474,
            777477477,
            777477744,
            777477747,
            777477774,
            777477777,
            777744444,
            777744447,
            777744474,
            777744477,
            777744744,
            777744747,
            777744774,
            777744777,
            777747444,
            777747447,
            777747474,
            777747477,
            777747744,
            777747747,
            777747774,
            777747777,
            777774444,
            777774447,
            777774474,
            777774477,
            777774744,
            777774747,
            777774774,
            777774777,
            777777444,
            777777447,
            777777474,
            777777477,
            777777744,
            777777747,
            777777774,
            777777777
        };
        //writer.println(l.indexOf(N)+1);

        //
        writer.println(Arrays.binarySearch(a, 0, a.length, N)+1);
        writer.flush();
    }
}
