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() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  string s;
  cin >> s;
  stack<char> st;
  int n = s.size();
  char mn[n + 1];
  mn[n] = 'z' + 1;
  for (int i = n - 1; i >= 0; i--) mn[i] = min(mn[i + 1], s[i]);
  string ans = "";
  for (int i = 0; i < s.size(); i++) {
    st.push(s[i]);
    while (!st.empty() && st.top() <= mn[i + 1]) {
      ans += (st.top());
      st.pop();
    }
  }
  cout << ans << endl;
  return 0;
}
