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 p;
string s, u = "";
multiset<char> ms;
vector<char> t;
int main() {
  cin >> s;
  for (int l = 0; l < s.size(); ++l) ms.insert(s[l]);
  for (int l = 0; l < s.size(); ++l) {
    while (t.size() > 0 && t[t.size() - 1] <= *ms.begin()) {
      u += t[t.size() - 1];
      t.pop_back();
    }
    if (s[l] == *ms.begin()) {
      ms.erase(ms.begin());
      u += s[l];
    } else {
      ms.erase(ms.lower_bound(s[l]));
      t.push_back(s[l]);
    }
  }
  for (int l = t.size() - 1; l >= 0; --l) u += t[l];
  cout << u;
  return 0;
}
