func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n;     cin >> n;     string s;     cin >> s;     vector<char> v;     int i = 0;     int j = 1;     int sum = -1;     while (sum < n - 1) {       sum = sum + j;       v.push_back(s[sum]);       j++;     }     for (auto it = v.begin(); it != v.end(); it++) {       cout << *it;     }   }   