func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base ::sync_with_stdio(false);     int n;     cin >> n;     int pass = 0, ans = 0;     while (n) {       ans += n;       ans += (pass * (n - 1));       pass++;       --n;     }     cout << ans;     return 0;   }   