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 f[100005];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> s;
  t.push(char('z' + 1));
  f[s.size() - 1] = s[s.size() - 1];
  for (int i = s.size() - 2; i >= 0; i--) {
    f[i] = min(f[i + 1], s[i]);
  }
  for (int i = 0; i < s.size(); i++) {
    while (t.top() <= f[i] && t.size() > 1) {
      u += t.top();
      t.pop();
    }
    t.push(s[i]);
  }
  while (t.size() > 1) {
    u += t.top();
    t.pop();
  }
  cout << u << endl;
  return 0;
}
