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.util.*;
import java.util.Map.Entry;
import java.lang.*;
import java.math.*;
import java.text.*;
import java.io.*;
		public final class Solve {
		static PrintWriter out = new PrintWriter(System.out); 
		static void flush() {
	 	out.flush();
	 	}
		static class FastReader {
	    BufferedReader br;
	    StringTokenizer st;
	
	    public FastReader() {
	    br = new BufferedReader(new
	    InputStreamReader(System.in));
	    }
	    static boolean isPalindrome(String str1, String str2) {
	    String str3 = str1+str2;
	    int i = 0, j = str3.length()-1;
	    while(i < j) {
	    char a = str3.charAt(i), b = str3.charAt(j);
	    if(a != b) return false;
	    i++;j--;
	    }
	    return true;
	    }
	    static boolean isPalindrome(String str) {
	    int i = 0, j = str.length()-1;
	    while(i < j) {
	    char a = str.charAt(i), b = str.charAt(j);
	    if(a != b) return false;
	    i++;j--;
	    }
	    return true;
	    }
	    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());}
	    static int fact(int n) {
	    if(n == 1) return 1;
	    return n * fact(n-1);
	   	}
	    public int[] readIntArray(int n) {
	    int[] arr = new int[n];
		for(int i=0; i<n; ++i)
		arr[i]=nextInt();
		return arr;
		}
	    public int[][] readIntArray(int m, int n){
		int[][] arr = new int[m][n];
		for(int i = 0;i<m;i++) 
		for(int j = 0;j<n;j++) 
		arr[i][j] = nextInt();
		return arr;
	    }
	    public String[] readStringArray(int n) {
		String[] arr = new String[n];
		for(int i=0; i<n; ++i)
		arr[i]= nextLine();
		return arr;
	    }
		static int gcd(int a, int b) { 
		if (b == 0) return a; 
		return gcd(b, a % b);  
		}
	    double nextDouble() {return Double.parseDouble(next());}
	    String nextLine() {
	    String str = "";
	    try{str = br.readLine();}
	    catch (IOException e) {e.printStackTrace();}
	    return str;}
	    }
		static void solve(String str) {
			StringBuilder sb = new StringBuilder();
			int x = str.length();
			for(int i=0;i<x;i++) {
				if(str.charAt(i) == '4') {
					sb.append(0);
				}
				else {
					sb.append(1);
				}
			}
		String res = sb.toString();
		int n = Integer.parseInt(res, 2);
		int to = 0;
		int p = 1;
		for(int i = 1;i<x;i++) {
			to += (int)Math.pow(2, p++);
		}
		out.println(to + n + 1);
		}
		public static void main(String args[]) throws Exception {
	    FastReader sc = new FastReader();
	    long start = System.currentTimeMillis();
	    String str = sc.next();
	    solve(str);
	    flush();
	    long end = System.currentTimeMillis();
	    NumberFormat formatter = new DecimalFormat("#0.00000");
	    //System.out.print("Execution time is " + formatter.format((end - start) / 1000d) + " seconds");
	    }
	}
		
		
		