#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n, i;
  cin >> n;
  string s, a, b;
  cin >> s;
  if (n % 2 == 0) {
    for (i = 0; i < n; i += 2) {
      a.push_back(s[i]);
      b.push_back(s[i + 1]);
    }
  } else {
    b.push_back(s[0]);
    for (i = 1; i < n; i += 2) {
      a.push_back(s[i]);
      b.push_back(s[i + 1]);
    }
  }
  reverse(begin(a), end(a));
  cout << a << b;
  return 0;
}
