func_code_string: #include <bits/stdc++.h>   using namespace std;   vector<long long int> v;   int bil;   void gen(long long int now) {     if (now > 1000000000LL) return;     if (now != 0) v.push_back(now);     gen(now * 10 + 4);     gen(now * 10 + 7);   }   int main(void) {     gen(0);     sort(v.begin(), v.end());     cin >> bil;     for (int i = 0; i < v.size(); i++) {       if (v[i] == bil) {         cout << i + 1 << endl;         return 0;       }     }   }   