#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n;
  cin >> n;
  char s[n];
  char r[n];
  cin >> s;
  for (int i = 0; i < n; i++) r[i] = s[i];
  if (n % 2 == 0) {
    long long int e = n / 2;
    for (int i = 1; i < n; i += 2) {
      r[e] = s[i];
      e++;
    }
    e = n / 2 - 1;
    for (int i = 0; i < n; i += 2) {
      r[e] = s[i];
      e--;
    }
    for (int i = 0; i < n; i++) cout << r[i];
    cout << "\n";
  } else {
    r[n / 2] = s[0];
    long long int p = n / 2;
    for (int i = 2; i < n; i += 2) {
      p++;
      r[p] = s[i];
    }
    p = n / 2;
    for (int i = 1; i < n; i += 2) {
      p--;
      r[p] = s[i];
    }
    for (int i = 0; i < n; i++) cout << r[i];
    cout << "\n";
  }
  return 0;
}
