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>
using namespace std;
int c[30];
int L;
char t[100010];
char s[100010];
int A, C;
int main() {
  scanf("%s", t + 1);
  L = strlen(t + 1);
  for (int i = 1; i <= L; i++) c[t[i] - 'a']++;
  for (int i = 1; i <= L; i++) {
    A++;
    s[A] = t[i];
    c[s[A] - 'a']--;
    while (C < 26 && !c[C]) C++;
    while (A && s[A] - 'a' <= C) {
      putchar(s[A]);
      A--;
    }
  }
  return 0;
}
