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[26];
int main() {
  cin.tie(0);
  cin.sync_with_stdio(0);
  string A, B;
  cin >> A;
  for (char c : A) {
    cnt[c - 'a']++;
  }
  int idx = 0;
  for (int a = 0; a < 26; a++) {
    while (!B.empty() && B.back() <= a + 'a') {
      cout << B.back();
      B.pop_back();
    }
    while (cnt[a]) {
      cnt[A[idx] - 'a']--;
      if (A[idx] - 'a' == a) {
        cout << A[idx];
      } else {
        B.push_back(A[idx]);
      }
      idx++;
    }
  }
}
