#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  string s, ss, sss;
  cin >> s;
  int j = 0;
  for (int i = n - 1; i >= 0; i--) {
    if (j % 2 == 0)
      ss += s[i];
    else
      sss += s[i];
    j++;
  }
  reverse(ss.begin(), ss.end());
  cout << sss << ss;
  cout << endl;
  return 0;
}
