#include <bits/stdc++.h>
const int M = 53;
int main() {
  int i, j, k;
  char s[M], t[M], c;
  i = 0;
  c = getchar();
  while (c != ' ' && c != '\n' && c != '\0') {
    s[i] = c;
    i++;
    c = getchar();
  }
  s[i] = '\0';
  j = strlen(s);
  for (k = 0, --j, i = j; j >= 0; j--) {
    if (j % 2) {
      t[j] = s[i];
      i--;
    } else {
      t[j] = s[k];
      k++;
    }
  }
  for (i = 0; i < strlen(s); i++) putchar(t[i]);
  return 0 - 0 - 0;
}
