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 = (int)1e6 + 7;
const int MOD = (int)1e9 + 7;
const int SQRT = (int)320;
int n;
string second;
char sf[N];
int main() {
  cin >> second;
  n = (int)second.size();
  sf[n] = 'z';
  for (int i = n - 1; i >= 0; i--) sf[i] = min(sf[i + 1], second[i]);
  string t;
  string ans;
  for (int i = 0; i < n; i++) {
    char x = second[i];
    t += x;
    while (!t.empty() && sf[i + 1] >= t.back()) {
      ans += t.back();
      t.pop_back();
    }
  }
  while (!t.empty()) {
    ans += t.back();
    t.pop_back();
  }
  cout << ans;
  return 0;
}
