#include <bits/stdc++.h>
using namespace std;
int main() {
  string a, b;
  cin >> a;
  b = a;
  int r = a.length();
  int even = r / 2;
  int odd = r / 2;
  if (r % 2 != 0) {
    for (int i = 0; i < r; i++) {
      if (i % 2 == 0) {
        cout << a[even];
        even--;
      } else {
        odd++;
        cout << a[odd];
      }
    }
  } else {
    for (int i = 0; i < r; i++) {
      if (i == 0 || i % 2 == 0) {
        even--;
        cout << a[even];
      } else {
        cout << a[odd];
        odd++;
      }
    }
  }
}
