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;
#pragma warning(disable : 4996)
char chars[200002];
int main() {
  string s;
  cin >> s;
  chars[s.length()] = 'z';
  for (int i = s.length() - 1; i >= 0; --i) {
    chars[i] = min(s[i], chars[i + 1]);
  }
  vector<char> vs;
  int id = 0;
  while (!vs.empty() || id < s.length()) {
    if (vs.empty() || chars[id] < vs[vs.size() - 1]) {
      vs.push_back(s[id++]);
      continue;
    }
    printf("%c", vs[vs.size() - 1]);
    vs.pop_back();
  }
  return 0;
}
