func_code_string: #include <bits/stdc++.h>   using namespace std;   int n;   long long res = 0;   int main() {     cin >> n;     long long tmp = 0;     int indez = 1;     for (int i = 1; i <= n - 1; i++) {       tmp += indez;       indez += 2;     }     res = tmp * 2;     res += (n * 2 - 1);     cout << res;     return 0;   }   