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;
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  string s;
  cin >> s;
  list<char> q;
  multiset<long long> ms;
  for (char c : s) {
    ms.insert(c);
    q.push_back(c);
  }
  string ans;
  list<long long> t;
  while (!q.empty()) {
    char nxt = *ms.begin();
    if (!t.empty() and t.back() <= nxt) {
      ans += t.back();
      t.pop_back();
    } else {
      while (!q.empty() and q.front() != nxt) {
        ms.erase(ms.find(q.front()));
        t.push_back(q.front());
        q.pop_front();
      }
      ms.erase(ms.find(q.front()));
      t.push_back(q.front());
      q.pop_front();
      ans += t.back();
      t.pop_back();
    }
  }
  while (!t.empty()) {
    ans += t.back();
    t.pop_back();
  }
  cout << ans << endl;
}
