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 n, i, j;
string s, t, u, v;
int main() {
  cin >> s;
  n = s.size();
  for (t = v = s, i = n - 2; i >= 0; i--) v[i] = min(s[i], v[i + 1]);
  for (i = 0; i < n; i++) {
    for (; j && v[i] >= t[j - 1];) u += t[--j];
    if (s[i] == v[i])
      u += s[i];
    else
      t[j++] = s[i];
  }
  for (; j;) u += t[--j];
  cout << u;
}
