func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int in, x = 0;     int cnt = 0, p = 1, ans = 0;     cin >> in;     for (int i = in; i > 0; i /= 10) {       if (i % 10 == 7) ans += p;       p *= 2;       cnt++;     }     if (cnt != 0) x = pow(2, cnt) - 2;     cout << ans + x + 1;   }   