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;
vector<int> place[256];
int main() {
  string s, t = "", ans = "";
  cin >> s;
  int len = s.size();
  for (int i = 0; i < len; ++i) {
    place[s[i]].push_back(i);
  }
  int start = 0;
  for (char target = 'a'; target <= 'z' and start < len; ++target) {
    int i = 0;
    while (t.size() and t.back() <= target) {
      ans.push_back(t[t.size() - 1]);
      t.pop_back();
    }
    while (i < place[target].size() and place[target][i] < start) ++i;
    for (; i < place[target].size(); ++i) {
      ans.push_back(target);
      for (int j = start; j < place[target][i]; ++j) {
        t.push_back(s[j]);
      }
      start = place[target][i] + 1;
    }
  }
  cout << ans;
  for (int i = t.size() - 1; i > -1; --i) cout << t[i];
}
