#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  string str;
  cin >> n >> str;
  for (int i = n - 2; i >= 0; i -= 2) cout << str[i];
  if (str.size() & 1)
    for (int i = 0; i < n; i += 2) cout << str[i];
  else
    for (int i = 1; i < n; i += 2) cout << str[i];
}
