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 MAX = 100100;
const int inf = 'z' + 1;
char s[MAX], t[MAX], m[MAX];
int main() {
  string s;
  cin >> s;
  int len = s.length();
  m[len] = inf;
  for (int i = len - 1; i >= 0; i--) {
    m[i] = min(m[i + 1], s[i]);
  }
  int j = 0;
  for (int i = 0; i < len; i++) {
    t[j] = s[i];
    j++;
    while (j > 0 && t[j - 1] <= m[i + 1]) {
      cout << t[--j];
    }
  }
  return 0;
}
