#include <bits/stdc++.h>
using namespace std;
int main() {
  char buff[200];
  scanf("%s", &buff);
  string word = buff;
  string result = "";
  if (!(word.size() % 2)) {
    for (int i = 0; i < word.size() / 2; i++) {
      result = result + word[word.size() - i - 1] + word[i];
    }
  } else {
    for (int i = 0; i < word.size() / 2; i++) {
      result = result + word[i] + word[word.size() - i - 1];
    }
    result += word[word.size() / 2];
  }
  reverse(result.begin(), result.end());
  printf("%s", result.c_str());
}
