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
#include <bits/stdc++.h>
using namespace std;
const int __ = 1e5 + 5;
char a[__], minn[__];
int num[30];
stack<char> S;
char get_min() {
  for (int i = ('a'); i <= ('z'); i++)
    if (num[i - 'a' + 1]) return i;
}
int main() {
  scanf("%s", a + 1);
  int len = strlen(a + 1);
  memset((minn), ('z'), sizeof(minn));
  for (int i = (1); i <= (len); i++) num[a[i] - 'a' + 1]++;
  for (int i = (len); i >= (1); i--) minn[i] = min(minn[i + 1], a[i]);
  for (int i = (1); i <= (len); i++) {
    S.push(a[i]);
    while (!S.empty() && S.top() <= minn[i + 1]) putchar(S.top()), S.pop();
  }
  while (!S.empty()) putchar(S.top()), S.pop();
  putchar('\n');
  return 0;
}
