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 MinimalString{
   public static void main(String[] arg) throws IOException{
     BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
     String s=br.readLine();
     Stack<Character> t=new Stack<>();
     StringBuilder result=new StringBuilder();
     int idx=0;
     for(char c='a';c<='z';c++){
	   while((t.size()>0)&&(t.peek()<=c)){
		   result.append(t.pop());
	   }
	   int nextPos=s.indexOf(c,idx);
	   while(nextPos>=0){
	      while(idx < nextPos){
			  t.push(s.charAt(idx++));
		  }
		  result.append(c);
		  idx++;
		  nextPos=s.indexOf(c,idx);
	   }

	 }
	 while(t.size()>0){
		 result.append(t.pop());
	 }
	 System.out.println(result.toString());
   }
}