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() {
  char c[100005];
  scanf("%s", c);
  vector<char> v;
  int count[26];
  int instk[26];
  memset(count, 0, sizeof(count));
  memset(instk, 0, sizeof(instk));
  int find = 0;
  for (int i = 0; c[i] != 0; i++) count[c[i] - 'a']++;
  while (count[find] == 0) find++;
  for (int i = 0; c[i] != 0; i++) {
    v.push_back(c[i]);
    count[c[i] - 'a']--;
    while (count[find] == 0) find++;
    while (!v.empty() && v.back() - 'a' <= find) {
      printf("%c", v.back());
      v.pop_back();
    }
  }
  while (!v.empty()) {
    printf("%c", v.back());
    v.pop_back();
  }
}
