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()
s+=('{')
ans=""
tmp=[]
m = ['z' for i in range(len(s)+1)]
for i in range(len(s)-1,-1,-1):
    m[i]=min(m[i+1],s[i])
#print(m)
for i in range(len(s)-1):
    tmp.append(s[i])
    while len(tmp) and tmp[-1]<=m[i+1]:
            ans += tmp.pop()
print(ans)