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
# Minimal String
s = input()
lenth = len(s)
mn = [0]*(lenth)
mnn = s[-1]
for i in range(lenth-1, -1, -1):
    mnn = min(mnn, s[i])
    mn[i] = mnn
st = []
for i in range(0, lenth):
    while(len(st) != 0 and st[-1] <= mn[i]):
        print(st.pop(), end='')
    st.append(s[i])
while(len(st) != 0):
    print(st.pop(), end='')
