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 N = 1e6 + 5;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  string s;
  cin >> s;
  char hh[N];
  hh[s.size() - 1] = s[s.size() - 1];
  for (int i = s.size() - 2; i >= 0; i--) {
    hh[i] = min(hh[i + 1], s[i]);
  }
  stack<char> v;
  for (int i = 0; i < s.size(); ++i) {
    while (!v.empty() && v.top() <= hh[i]) {
      cout << v.top();
      v.pop();
    }
    if (s[i] == hh[i]) {
      cout << s[i];
    } else {
      v.push(s[i]);
    }
  }
  while (!v.empty()) {
    cout << v.top();
    v.pop();
  }
}
