#include <bits/stdc++.h>
#pragma warning(disable : 4996 6031)
using namespace std;
void solve();
int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  solve();
  return 0;
}
void solve() {
  int n;
  cin >> n;
  string s;
  cin >> s;
  if (s.length() <= 2) {
    cout << s << endl;
    return;
  }
  string t = "";
  for (int i = n - 2; i >= 0; i -= 2) t += s[i];
  if (n & 1)
    for (int i = 0; i < n; i += 2) t += s[i];
  else
    for (int i = 1; i < n; i += 2) t += s[i];
  cout << t << endl;
}
