#include <bits/stdc++.h>
using namespace std;
int main() {
  string s = "", t = "";
  cin >> s;
  if (s.size() == 1)
    cout << s;
  else {
    if (s.size() % 2 == 1) {
      t = s[s.size() / 2];
      for (int i = s.size() / 2 + 1; i < s.size(); ++i) {
        t = t + s[i] + " ";
      }
      int p = 2;
      for (int i = s.size() / 2 - 1; i >= 0; i--) {
        t[p] = s[i];
        p += 2;
      }
    }
    if (s.size() % 2 == 0) {
      t = t + s[s.size() / 2 - 1] + s[s.size() / 2];
      for (int i = s.size() / 2 - 2; i >= 0; --i) {
        t = t + s[i] + " ";
      }
      int p = 3;
      for (int i = s.size() / 2 + 1; i < s.size(); i++) {
        t[p] = s[i];
        p += 2;
      }
    }
  }
  cout << t << endl;
  return 0;
}
