func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n;     cin >> n;     int t = n % 4;     int a = 0;     for (int i = 0; i < 4; i++) {       if ((i * 7) % 4 == t) a = i;     }     int b = -1, c;     for (int j = (n - a) / 4 * 4 + a; j >= a; j -= 4) {       if ((n - 7 * j) % 4 == 0 && (n - 7 * j >= 0)) {         c = j;         b = (n - 7 * j) / 4;         break;       }     }     if (b == -1) {       cout << -1;       return 0;     }     for (int i = 0; i < b; i++) cout << 4;     for (int i = 0; i < c; i++) cout << 7;     return 0;   }   