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