#include <bits/stdc++.h>
using namespace std;
int main() {
  string s, ss = "";
  int n;
  cin >> n >> s;
  if (n % 2 != 0) {
    ss = s[0];
    bool flag = false;
    for (int i = 1; i < s.size(); i++) {
      if (!flag)
        ss = s[i] + ss;
      else
        ss += s[i];
      flag = !flag;
    }
  } else {
    bool flag = false;
    for (int i = 0; i < s.size(); i++) {
      if (!flag)
        ss = s[i] + ss;
      else
        ss += s[i];
      flag = !flag;
    }
  }
  cout << ss << endl;
  return 0;
}
