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)1e5 + 5, mod = (int)0;
int best[N], q[N];
int main() {
  string s;
  cin >> s;
  int n = (int)s.size();
  best[n] = 1e9;
  for (int j = n - 1; j >= 0; --j) {
    s[j] -= 'a';
    best[j] = min(best[j + 1], (int)s[j]);
  }
  string res = "";
  int t = 0;
  for (int j = 0; j < n; ++j) {
    q[t++] = s[j];
    while (t > 0 && q[t - 1] <= best[j + 1]) res += char(q[t - 1] + 'a'), --t;
  }
  cout << res << endl;
}
