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() {
  string s, str, u;
  cin >> s;
  stack<char> t;
  u = "";
  vector<long long> A(26);
  for (long long i = 0; i < s.length(); i++) A[s[i] - 'a']++;
  for (long long i = 0; i < s.length(); i++) {
    t.push(s[i]);
    A[s[i] - 'a']--;
    char ch;
    for (long long i = 0; i < 26; i++) {
      if (A[i] > 0) {
        ch = 'a' + i;
        break;
      }
    }
    while (!t.empty() && t.top() <= ch) {
      u += t.top();
      t.pop();
    }
  }
  while (!t.empty()) {
    u += t.top();
    t.pop();
  }
  cout << u;
  return 0;
}
