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 cnt[322], cur = 0;
string s;
stack<int> t;
int main() {
  cin >> s;
  for (int i = 0; i < s.size(); i++) cnt[s[i]]++;
  for (int i = 'a'; i <= 'z'; i++) {
    while (t.size() && t.top() <= i) {
      cout << char(t.top());
      t.pop();
    }
    while (cnt[i]) {
      cnt[s[cur]]--;
      if (s[cur] != i)
        t.push(s[cur]);
      else
        cout << char(i);
      cur++;
    }
  }
  while (t.size()) {
    cout << char(t.top());
    t.pop();
  }
  return 0;
}
