#include <bits/stdc++.h>   using namespace std;   int main() {     string s;     cin >> s;     int ans = 0;     int n = s.size();     for (int i = 0; i < n; i++) ans += (1 << i);     for (int i = 0; i < n; i++) {       if (s[i] ==  7 ) ans += (1 << (n - i - 1));     }     cout << ans;   }   