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 MAXN = 1e5 + 10;
int n;
string s, t;
char ch[MAXN];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> s;
  n = s.size();
  for (int i = n - 1; ~i; i--)
    if (i == n - 1)
      ch[i] = s[i];
    else
      ch[i] = min(s[i], ch[i + 1]);
  string temp;
  int cur = 0;
  while (t.size() < n) {
    if (temp.empty() || (cur < n && ch[cur] < temp.back())) {
      while (s[cur] != ch[cur]) temp.push_back(s[cur++]);
      t.push_back(s[cur++]);
    } else {
      t += temp.back();
      temp.pop_back();
    }
  }
  cout << t << "\n";
  return 0;
}
