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;
string s, u;
stack<char> t;
char arr[100001];
int main() {
  cin >> s;
  arr[s.size() - 1] = s[s.size() - 1];
  for (int i = s.size() - 2; i >= 0; i--) arr[i] = min(arr[i + 1], s[i]);
  for (int i = 0; i < s.size(); i++) {
    while (!t.empty() and t.top() <= arr[i]) {
      u += t.top();
      t.pop();
    }
    if (s[i] == arr[i])
      u += s[i];
    else
      t.push(s[i]);
  }
  cout << u;
  while (!t.empty()) {
    cout << t.top();
    t.pop();
  }
  return 0;
}
