func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     long long t;     cin >> t;     long long k = 0, m = 1;     while (t > 0) {       if (t % 10 == 4) {         k = k + m;       } else {         k = k + 2 * m;       }       m = m * 2;       t = t / 10;     }     cout << k;   }   