#include <bits/stdc++.h>
using namespace std;
int main() {
  long long a;
  string n;
  cin >> a >> n;
  string ans(1, n[0]);
  for (long long i = 1; i < a; ++i) {
    if ((a - i) % 2 == 0) {
      ans = n[i] + ans;
    } else {
      ans = ans + n[i];
    }
  }
  cout << ans << endl;
}
