#include <bits/stdc++.h>
int main() {
  int n, in, f, a = 0;
  scanf("%d", &n);
  char st[n + 1], dst[n];
  scanf("%s", st);
  if (n % 2 == 0)
    in = n / 2, f = 0;
  else
    in = (n + 1) / 2, f = 1;
  in -= 1;
  for (int i = 0; i < n; i++) {
    if (f == 0) {
      if (i % 2 == 0)
        in = in - a;
      else
        in = in + a;
      dst[in] = st[i];
      a++;
    } else if (f == 1) {
      if (i % 2 == 0)
        in += a;
      else
        in -= a;
      dst[in] = st[i];
      a++;
    }
  }
  for (int i = 0; i < n; i++) printf("%c", dst[i]);
  return 0;
}
