#include <bits/stdc++.h>
using namespace std;
int main() {
  string code;
  int len;
  cin >> len;
  cin >> code;
  string res = string(1, code[0]);
  int start = 1;
  if (len % 2 == 0) {
    res.append(1, code[1]);
    start = 2;
  }
  bool isOdd = (len % 2 == 1);
  for (int i = start; i < len; ++i) {
    if ((i + (int)isOdd) % 2 == 0) {
      res.insert(0, 1, code[i]);
    } else {
      res.append(1, code[i]);
    }
  }
  cout << res;
  return 0;
}
