#include <bits/stdc++.h>
using namespace std;
int N;
string s;
string result;
int main() {
  cin >> N;
  cin >> s;
  result = s;
  result[(N - 1) / 2] = s[0];
  int sign = N % 2 == 0 ? 1 : -1;
  int val = 1;
  int start = (N - 1) / 2;
  for (int i = 1; i < N; ++i, sign *= -1, val++)
    start = start + val * sign, result[start] = s[i];
  cout << result;
  return 0;
}
