#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7, N = 2007;
int main() {
  int n;
  string s, ans;
  cin >> n >> s;
  while (!s.empty()) {
    if (s.size() & 1)
      ans += s[0];
    else
      ans = s[0] + ans;
    s.erase(0, 1);
  }
  cout << ans;
  return 0;
}
