#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, j = 0;
  cin >> n;
  double k = n;
  string slov1, slov;
  cin >> slov;
  for (int i = n - 2; i >= 0; i -= 2, j++) {
    slov1 = slov1 + slov[i];
  }
  if (n % 2 == 0) {
    for (int i = 1; i < n; i += 2) slov1 = slov1 + slov[i];
  } else {
    for (int i = 0; i < n; i += 2) slov1 = slov1 + slov[i];
  }
  cout << slov1;
  return 0;
}
