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;
int main() {
  ios_base::sync_with_stdio(false);
  string s;
  stack<char> t;
  vector<char> u;
  int sn[26] = {0}, un[26] = {0}, tn[26] = {0};
  cin >> s;
  int min = 26;
  int l = s.length();
  for (int i = 0; i < l; i++) {
    sn[(int)s[i] - 'a']++;
    if (((int)s[i] - 'a') < min) min = (int)s[i] - 'a';
  }
  for (int i = 0; i < l; i++) {
    if (((int)s[i] - 'a') != min)
      t.push(s[i]), sn[(int)s[i] - 'a']--;
    else
      u.push_back(s[i]), sn[(int)s[i] - 'a']--;
    while (sn[min] == 0) min++;
    while (t.size() > 0 && min >= ((int)t.top() - 'a'))
      u.push_back(t.top()), t.pop();
  }
  while (t.size()) u.push_back(t.top()), t.pop();
  for (int i = 0; i < u.size(); i++) cout << u[i];
  return 0;
}
