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 int n;
long long int arr[26];
string s;
stack<char> t;
long long int find_min();
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> s;
  for (long long int i = 0; i < s.size(); ++i) arr[s[i] - 'a']++;
  long long int min = find_min();
  auto iter = s.begin();
  while (iter != s.end()) {
    if (!t.empty() && t.top() <= min + 'a') {
      cout << t.top();
      t.pop();
    } else {
      arr[*iter - 'a']--;
      if (*iter == (min + 'a')) {
        cout << *iter;
        min = find_min();
      } else
        t.push(*iter);
      iter++;
    }
  }
  while (!t.empty()) {
    cout << t.top();
    t.pop();
  }
  return 0;
}
long long int find_min() {
  for (int i = 0; i < 26; ++i) {
    if (arr[i] != 0) {
      return i;
    }
  }
  return -1;
}
