Petya recieved a gift of a string s with length up to 105 characters for his birthday. He took two more empty strings t and u and decided to play a game. This game has two possible moves:

  * Extract the first character of s and append t with this character. 
  * Extract the last character of t and append u with this character. 



Petya wants to get strings s and t empty and string u lexicographically minimal.

You should write a program that will help Petya win the game.

Input

First line contains non-empty string s (1 ≤ |s| ≤ 105), consisting of lowercase English letters.

Output

Print resulting string u.

Examples

Input

cab


Output

abc


Input

acdb


Output

abdc
#include <bits/stdc++.h>
char c, a[100003], s[100003];
int i = 1, j, n, t;
int main() {
  for (scanf("%s", a + 1); a[++n];)
    ;
  for (--n, c = 97; c < 123; ++c) {
    for (; t && s[t] <= c; putchar(s[t--]))
      ;
    for (j = n; j && a[j] != c; --j)
      ;
    for (; i <= j; ++i)
      if ((s[++t] = a[i]) == c) putchar(s[t--]);
  }
  for (; t; putchar(s[t--]))
    ;
}
