#include <bits/stdc++.h>
using namespace std;
const long long MAX = 5e2 + 5;
const long long INF = 1e18;
const long long mod = 1e8;
int main() {
  string a;
  cin >> a;
  int i, l, j, p, q;
  l = a.length();
  p = l / 2 + l % 2;
  vector<char> b;
  for (i = 0; i < p; i++) b.push_back(a[i]);
  reverse(b.begin(), b.end());
  string c = "";
  for (auto z : b) {
    c += z;
    if (i < l) {
      c += a[i];
      i++;
    }
  }
  cout << c;
}
