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;
const int N = 100004;
char s[N];
char u[N];
char st[N];
int cnt[26];
int top;
int calc(int x) {
  int res = 0;
  for (int i = 0; i < x; i++) res += cnt[i];
  return res;
}
int main() {
  scanf("%s", s);
  int n = strlen(s);
  int i;
  for (i = 0; i < n; i++) {
    cnt[s[i] - 'a']++;
  }
  int x = 0;
  for (i = 0; i < n; i++) {
    cnt[s[i] - 'a']--;
    st[top++] = s[i];
    while (top > 0 && (calc(st[top - 1] - 'a') == 0)) {
      top--;
      u[x++] = st[top];
    }
  }
  printf("%s\n", u);
  return 0;
}
