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;
vector<char> a;
int main() {
  string s;
  cin >> s;
  int n;
  n = s.size();
  a.resize(n);
  a[n - 1] = s[n - 1];
  for (int i = n - 2; i >= 0; i--) {
    a[i] = min(s[i], a[i + 1]);
  }
  stack<char> b;
  for (int i = 0; i < n; i++) {
    while (!b.empty() && b.top() <= a[i]) {
      printf("%c", b.top());
      b.pop();
    }
    b.push(s[i]);
  }
  while (!b.empty()) {
    printf("%c", b.top());
    b.pop();
  }
}
