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=raw_input()#"putainborderldemerdre"*10000#
t=""
u=""
n=len(s)

dp={}
for k in range(n):
    if s[k] not in dp:
        dp[s[k]]=[]
    dp[s[k]]+=[k]
corr=0

while len(s)>0:
    a=min(s)
    allas=[k-corr for k in dp[a] if k>=corr]
  #  print s,t,u,allas,a
    u+=a*len(allas)
    corr+=allas[-1]+1
    bf=0
    for k in range(len(allas)):
        t+=s[bf:allas[k]]
        bf=allas[k]+1
    s=s[allas[-1]+1:]
    if len(s)>0:
        a=min(s)
        while len(t)>0 and t[-1]<=a:
            u+=t[-1]
            t=t[:-1]
   # print s,t,u,allas,a
u+=t[::-1]
if len(u)!=n:
    print u
    1/0
print u