#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  string Decod, s;
  cin >> n >> s;
  int i = 0;
  while (n) {
    if (n % 2 != 0) {
      Decod += s[i];
    } else {
      Decod = s[i] + Decod;
    }
    n = n - 1;
    i++;
  }
  cout << Decod << endl;
}
