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
s=input()
t=[]
u=[]
k=[0]*26
for i in s:
    k[ord(i)-97]+=1
for i in s:
    t+=i
    k[ord(i)-97]-=1
    while t and sum(k[0:ord(t[-1])-97])==0:
        u+=t[-1]
        t.pop()
print("".join(u))
    