func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n;     cin >> n;     vector<int> digs;     while (n % 10 != 0) {       digs.push_back(n % 10);       n /= 10;     }     reverse(digs.begin(), digs.end());     int ans = 1;     for (int i = 0; i < digs.size(); i++) {       ans *= 2;       if (digs[i] == 7) {         ans++;       }     }     cout << ans - 1 << endl;     return 0;   }   