#include <bits/stdc++.h>
using namespace std;
int n;
string str;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> n;
  cin >> str;
  string str2;
  str2.resize(n);
  int i = 0, l, r;
  if (n % 2 == 1) {
    str2[n / 2] = str[0];
    ++i;
    l = n / 2 - 1;
    r = n / 2 + 1;
  } else {
    l = n / 2 - 1;
    r = n / 2;
  }
  int j = i + 1;
  while (l >= 0) {
    str2[l] = str[i];
    i += 2;
    --l;
  }
  while (r < n) {
    str2[r] = str[j];
    j += 2;
    ++r;
  }
  cout << str2 << '\n';
}
