#include <bits/stdc++.h>
using namespace std;
signed main() {
  string s, ans;
  cin >> s;
  ans = s;
  int left = 0, right = s.size() - 1, i = s.size() - 1;
  if (s.size() % 2 == 0) {
    while (left < right) {
      ans[i] = s[right];
      right--;
      i--;
      ans[i] = s[left];
      left++;
      i--;
    }
  } else {
    while (left <= right) {
      ans[i] = s[left];
      left++;
      i--;
      if (left >= right) {
        break;
      }
      ans[i] = s[right];
      right--;
      i--;
    }
  }
  cout << ans;
}
