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;
int main(void) {
  char c[100001];
  cin >> c;
  int n = strlen(c);
  stack<char> t;
  char q[n + 1];
  q[n] = 'z' + 1;
  for (int i = n - 1; i >= 0; i--) q[i] = (c[i] < q[i + 1] ? c[i] : q[i + 1]);
  for (int i = 0; i < n; i++) {
    t.push(c[i]);
    while (!t.empty() && t.top() <= q[i + 1]) printf("%c", t.top()), t.pop();
  }
  printf("\n");
  return 0;
}
