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() {
  string s;
  cin >> s;
  multiset<char> ms;
  for (char c : s) ms.insert(c);
  string t, u;
  for (int i = 0; i < (s.size()); i++) {
    ms.erase(ms.find(s[i]));
    t += s[i];
    while (!t.empty() && ms.lower_bound(t.back()) == ms.begin()) {
      u += t.back();
      t.pop_back();
    }
  }
  cout << u << endl;
}
