#include <bits/stdc++.h>
int main() {
  int n;
  std::string stri;
  std::cin >> n >> stri;
  for (int i = n - 2; i >= 0; i -= 2) std::cout << stri.at(i);
  for (int i = ((n % 2) ^ 1); i <= n - 1; i += 2) std::cout << stri.at(i);
  std::cout << std::endl;
}
