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
from collections import Counter
s=input()
t=[]
u=[]
s=list(s)
cc=dict(Counter(s))
f=sorted(list(set(s)))
ch=f[0]
k=0
for i in range(len(s)):
    t.append(s[i])
    cc[s[i]]-=1
    while cc[ch]==0:
        k+=1
        try:
            ch=f[k]
        except:
            break
    while t[-1]<=ch:
        gg=t.pop()
        u.append(gg)
        if not t:
            break
    #print(s[i],"".join(u),ch)

while t:
    gg=t.pop()
    u.append(gg)
print("".join(u))