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 t[100005] = {};
  string s;
  stack<char> mystack;
  cin >> s;
  t[s.length() - 1] = s[s.length() - 1];
  for (int i = s.length() - 2; i >= 0; i--) t[i] = min(t[i + 1], s[i]);
  for (int i = 0; i < s.length(); i++) {
    if (mystack.empty())
      mystack.push(s[i]);
    else {
      while (!mystack.empty()) {
        if (mystack.top() <= t[i]) {
          cout << mystack.top();
          mystack.pop();
        } else
          break;
      }
      mystack.push(s[i]);
    }
  }
  while (!mystack.empty()) {
    cout << mystack.top();
    mystack.pop();
  }
  return 0;
}
