#include <bits/stdc++.h>
using namespace std;
inline unsigned long long int in() {
  unsigned long long int p = 0;
  register char ch = 0;
  while (ch < '0' or ch > '9') {
    ch = getchar();
  }
  while (ch >= '0' and ch <= '9') {
    p = (p << 1) + (p << 3) + ch - '0';
    ch = getchar();
  }
  return p;
}
inline void dukya(unsigned long long int n) {
  unsigned long long int N = n, rev, count_ = 0;
  rev = N;
  if (N == 0) {
    putchar('0');
    putchar('\n');
    return;
  }
  while ((rev % 10) == 0) {
    count_++;
    rev /= 10;
  }
  rev = 0;
  while (N != 0) {
    rev = (rev << 3) + (rev << 1) + N % 10;
    N /= 10;
  }
  while (rev != 0) {
    putchar(rev % 10 + '0');
    rev /= 10;
  }
  while (count_--) putchar('0');
  putchar('\n');
}
int main() {
  string t;
  cin >> t;
  string s;
  long long int i = 0, j = 0;
  if (t.size() % 2 == 0) {
    s.push_back(t[floor(t.size() / 2.0) - 1]);
    i = floor(t.size() / 2.0) - 2;
    j = floor(t.size() / 2.0);
  } else {
    s.push_back(t[floor(t.size() / 2.0)]);
    i = floor(t.size() / 2.0) - 1;
    j = floor(t.size() / 2.0) + 1;
  }
  for (; i >= 0 && j < t.size(); --i, ++j) {
    s.push_back(t[j]);
    s.push_back(t[i]);
  }
  while (j < t.size()) {
    s.push_back(t[j]);
    ++j;
  }
  cout << s << "\n";
  return 0;
}
