#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  string word, neww = "";
  cin >> word;
  for (int i = 0; i < n; i++) {
    if (i % 2 == 0) {
      neww = neww + word[i];
      continue;
    }
    neww = word[i] + neww;
  }
  if (n % 2 == 0) reverse(neww.begin(), neww.end());
  return cout << neww, 0;
}
