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;
  string ans = "";
  stack<char> sc;
  int len = s.size();
  int arr[27] = {0};
  int low = 25;
  for (int i = 0; i < len; i++) {
    arr[s[i] - 97]++;
    if (s[i] - 97 < low) low = s[i] - 97;
  }
  for (int i = 0; i < len; i++) {
    sc.push(s[i]);
    arr[s[i] - 97]--;
    for (int j = low; j <= 25; j++) {
      if (arr[j] != 0) {
        low = j;
        break;
      }
    }
    while (!sc.empty() && sc.top() - 97 <= low) {
      ans.push_back(sc.top());
      sc.pop();
    }
  }
  while (!sc.empty()) {
    ans.push_back(sc.top());
    sc.pop();
  }
  cout << ans << endl;
  return 0;
}
