func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(false);     cin.tie(0);     long long n;     cin >> n;     string s;     while (1) {       if (n % 7 == 0) {         n = n / 7;         for (long long i = 0; i < n; i++) s.push_back( 7 );         break;       } else {         if (n > 0) {           s.push_back( 4 );           n -= 4;         } else {           cout << -1;           return 0;         }       }     }     if (s.empty())       cout << -1;     else       cout << s;   }   