#include <bits/stdc++.h>
using namespace std;
void boost() { ios_base::sync_with_stdio(0); }
int n;
string s;
vector<char> v;
vector<char> v2;
int main() {
  boost();
  cin >> n >> s;
  for (int i = n - 1; i >= 0; i -= 2) {
    v.push_back(s[i]);
  }
  for (int i = n - 2; i >= 0; i -= 2) {
    v2.push_back(s[i]);
  }
  for (int i = 0; i < v2.size(); i++) {
    cout << v2[i];
  }
  for (int i = v.size() - 1; i >= 0; i--) {
    cout << v[i];
  }
  exit(0);
}
