#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("Ofast")
using namespace std;
signed main() {
  string s1;
  cin >> s1;
  deque<char> d;
  int sz = s1.size();
  if (sz % 2 == 1) {
    for (int i = 0; i < sz;) {
      if (i == sz - 1) {
        d.push_front(s1[sz - 1]);
        sz--;
        i++;
      } else {
        d.push_front(s1[i]);
        d.push_front(s1[sz - 1]);
        sz--;
        i++;
      }
    }
    for (int i = 0; i < d.size(); ++i) {
      cout << d[i];
    }
  } else {
    for (int i = 0; i < sz;) {
      if (i == sz - 1) {
        d.push_front(s1[sz - 1]);
        sz--;
        i++;
      } else {
        d.push_front(s1[sz - 1]);
        d.push_front(s1[i]);
        sz--;
        i++;
      }
    }
    for (int i = 0; i < d.size(); ++i) {
      cout << d[i];
    }
  }
  return 0;
}
