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;
long long binpow(long long a, long long b) {
  long long res = 1;
  while (b > 0) {
    if (b & 1) res = res * a;
    a = a * a;
    b >>= 1;
  }
  return res;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  string s;
  cin >> s;
  int n = s.length();
  stack<char> element;
  char arr[n + 1];
  arr[n] = 123;
  for (int i = n - 1; i >= 0; i--) {
    if (min(arr[i + 1], s[i]) == s[i])
      arr[i] = s[i];
    else
      arr[i] = arr[i + 1];
  }
  for (int i = 0; i < n; i++) {
    element.push(s[i]);
    while (!element.empty() && element.top() <= arr[i + 1]) {
      cout << element.top();
      element.pop();
    }
  }
}
