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, u;
  getline(cin, s);
  stack<char> stk;
  vector<int> mi(s.size() + 1, 0);
  mi[s.size()] = 10000;
  for (int i = s.size() - 1; i >= 0; i--) mi[i] = min((int)s[i], mi[i + 1]);
  for (int i = 0; i < s.size(); i++) {
    stk.push(s[i]);
    while (!stk.empty() && stk.top() <= mi[i + 1]) {
      cout << stk.top();
      stk.pop();
    }
  }
  while (!stk.empty()) {
    cout << stk.top();
    stk.pop();
  }
}
