#include <bits/stdc++.h>
int main() {
  int n;
  std::string code, word;
  std::cin >> n >> code;
  word = code[n - 1];
  for (int i = 1; i < n; ++i)
    word =
        word.substr(0, i / 2) + code[n - i - 1] + word.substr(i / 2, i - i / 2);
  std::cout << word;
  return 0;
}
