#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  string s1, s2[n];
  cin >> s1;
  if (n != 1) {
    if (n % 2 != 0) {
      int m1 = (n / 2) - 1, m2 = (n / 2) + 1;
      s2[n / 2] = s1[0];
      for (int a = 1; a != n; a++) {
        if (a % 2 != 0) {
          s2[m1--] = s1[a];
        } else
          s2[m2++] = s1[a];
      }
    } else if (n % 2 == 0) {
      int m1 = (n / 2) - 2, m2 = (n / 2);
      s2[(n / 2) - 1] = s1[0];
      for (int a = 1; a != n - 1; a++) {
        if (a % 2 == 0) {
          s2[m1--] = s1[a];
        } else
          s2[m2++] = s1[a];
      }
      s2[n - 1] = s1[n - 1];
    }
    for (int a = 0; a != n; a++) {
      cout << s2[a];
    }
  } else
    cout << s1;
  return 0;
}
