func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     long long n, pl = 4, otv = 1;     cin >> n;     if (n > 1) {       for (long long i = 1; i < n; i++) {         otv = otv + pl;         pl += 4;       }     } else if (n == 1) {       otv = 1;     }     cout << otv;   }   