#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  string s, s1 = "", s2 = "";
  cin >> n >> s;
  reverse(s.begin(), s.end());
  for (int i = 0; i < s.size(); ++i) {
    if (i % 2 == 0)
      s1 += s[i];
    else
      s2 += s[i];
  }
  reverse(s1.begin(), s1.end());
  cout << s2 << s1;
  return 0;
}
