#include <bits/stdc++.h>   using namespace std;   int main() {     long long n, mid;     bool flag;     string str;     char ans[3000];     cin >> n;     cin >> str;     if (n % 2 == 0) {       mid = (n / 2) - 1;       flag = true;     } else {       mid = (n - 1) / 2;       flag = false;     }     long long k = 1, cnt = 0;     ans[mid] = str[0];     for (long long i = 1; i < str.size(); i++) {       cnt++;       if (flag) {         ans[mid + k] = str[i];       } else {         ans[mid - k] = str[i];       }       if (cnt == 2) {         k++;         cnt = 0;       }       flag = !flag;     }     for (long long i = 0; i < n; i++) {       cout << ans[i];     }     return 0;   }   