#include <bits/stdc++.h>
using namespace std;
int n, br, k;
string s;
char s2[2500];
int main() {
  scanf("%d", &n);
  cin >> s;
  k = n;
  for (int i = 0; i <= n - 1; i++) s2[i] = '*';
  for (int i = 0; i <= n - 1; i++)
    for (int j = 0; j <= n - 1; j++) {
      if (s2[j] < 'a' || s2[j] > 'z') {
        br++;
        if (k % 2 == 0) {
          if (br == k / 2) {
            s2[j] = s[i];
            k--;
            br = 0;
            break;
          }
        } else {
          if (br == k / 2 + 1) {
            s2[j] = s[i];
            k--;
            br = 0;
            break;
          }
        }
      }
    }
  for (int i = 0; i <= n - 1; i++) printf("%c", s2[i]);
  return 0;
}
