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