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
import java.io.*;
import java.util.*;

public class Codeforces
{
    public static void main(String args[])throws Exception
    {
        BufferedReader bu=new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb=new StringBuilder();
        String s=bu.readLine().trim();
        int n=s.length(),i;
        char min[]=new char[n+1];
        min[n]='|';
        for(i=n-1;i>=0;i--)
        min[i]=(char)Math.min(min[i+1],s.charAt(i));

        int d=0,q[]=new int[n],j=0; i=0;
        while(i<n)
        {
            q[d++]=s.charAt(j++);
            while(d>0 && q[d-1]<=min[j])
            {
                sb.append((char)q[--d]);
                i++;
            }
        }
        System.out.print(sb);
    }
}