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
import sys
import array
s = sys.stdin.readline().replace("\n", "")
n = len(s)
dp = array.array('i', range(n))
m = "z"
for i in range(n-1, -1, -1):
    m = min(m, s[i])
    dp[i] = ord(m)
t = ""
lt = 0
ans = ""
i = 0
while i < n:
    if lt != 0 and t[-1] <= chr(dp[i]):
        ans += t[-1]
        t = t[:lt - 1]
        lt -= 1
    elif s[i] == chr(dp[i]):
        ans += s[i]
        i += 1
    elif s[i] != chr(dp[i]):
        t += s[i]
        lt += 1
        i += 1
ans += t[::-1]
print(ans)