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."

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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.awt.geom.Area;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.*;
import java.util.Map.Entry;

/*
    int n      = sc.nextInt();        // read input as integer
    long k     = sc.nextLong();       // read input as long
    double d   = sc.nextDouble();     // read input as double
    String str = sc.next();           // read input as String
    String s   = sc.nextLine();       // read whole line as String
*/
public class Main {

    public static PrintWriter out;

    public static void main(String args[]) {

        MyScanner in = new MyScanner();
        int n = in.nextInt();
        String temp = String.valueOf(n);
        int[] newGuess = new int[temp.length()];
        for (int i = 0; i < temp.length(); i++) {
            newGuess[i] = temp.charAt(i) - '0';
        }

        System.out.println(getNumber(newGuess));
    }

    private static int getNumber(int[] newGuess) {

        int count = 0;
        int factor = 0;
        for (int i = newGuess.length - 1; i >= 0; i--) {
            if (i != newGuess.length - 1)
                count += factor;
            else
                factor = 1;

            if (i != newGuess.length - 1 && newGuess[i] == 7) {
                count += factor;
            }

            factor *= 2;

            if (i==newGuess.length - 1 && newGuess[newGuess.length - 1] == 7)
                count = 1;
        }
        return count + 1;
    }

    public static class MyScanner {

        BufferedReader br;
        StringTokenizer st;

        public MyScanner() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }

    }

}