#include <bits/stdc++.h>
using namespace std;
inline void DeCode(string Code, long long size) {
  if (size % 2 == 0) {
    for (long long i = size / 2; i < size; ++i)
      cout << Code[size - i - 1] << Code[i];
    return;
  }
  for (long long i = size / 2; i < size; ++i)
    if (i == size / 2)
      cout << Code[size - i - 1];
    else
      cout << Code[i] << Code[size - i - 1];
  return;
}
signed main() {
  string Code;
  cin >> Code;
  DeCode(Code, Code.size());
  return 0;
}
