func_code_string: #include <bits/stdc++.h>   using namespace std;   int n;   long long s, x;   int main() {     srand(time(NULL));     cin >> n;     n--;     s = 1;     x = 12;     while (n) {       s += x;       x += 12;       n--;     }     cout << s << endl;     return 0;   }   