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()
leng = len(s)
minarray = [0]*leng
mins = 'z'
for i in range(leng-1,-1,-1):
    if s[i] < mins:
        mins = s[i]
    minarray[i] = mins
    
st = []
fist = []

for i in range(leng):
    while st != [] and st[-1] <= minarray[i]:
        fist.append(st[-1])
        st.pop()
    if s[i] == minarray[i]:
        fist.append(s[i])    
    else:
        st.append(s[i])   
while st != []:
    fist.append(st[-1])
    st.pop()
print(''.join(fist))    