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;
char mn[1000005];
stack<char> S;
int main() {
  string s;
  cin >> s;
  int len = s.length();
  mn[len] = 'z' + 1;
  for (int i = len - 1; i >= 0; i--) mn[i] = min(mn[i + 1], s[i]);
  int ptr = 0;
  while (!S.empty() || ptr < len) {
    while (!S.empty() && S.top() <= mn[ptr]) {
      cout << S.top();
      S.pop();
    }
    if (ptr == len) break;
    S.push(s[ptr++]);
  }
  cout << endl;
  return 0;
}
