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;
const int k = 1000022;
char m[k];
char u[k];
char t[k];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ;
  int n;
  string s;
  cin >> s;
  n = s.size();
  m[n - 1] = s[n - 1];
  for (int i = n - 2; i >= 0; i--) {
    m[i] = min(s[i], m[i + 1]);
  }
  int i = 0, top = 0, tt = 0;
  while (i < n) {
    while (top && t[top] <= m[i]) u[tt++] = t[top--];
    t[++top] = s[i++];
  }
  while (top) u[tt++] = t[top--];
  for (int i = 0; i < n; i++) cout << u[i];
  cout << endl;
  return 0;
}
