#include <bits/stdc++.h>
using namespace std;
int N, i, j;
string S, R;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> N >> S;
  for (i = N - 2; i >= 0; i -= 2) {
    R = R + S[i];
  }
  if (N % 2 == 0)
    i = 1;
  else
    i = 0;
  for (i = i; i < N; i += 2) {
    R = R + S[i];
  }
  cout << R << endl;
}
