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 main() {
  string x;
  cin >> x;
  stack<char> st;
  string ans;
  vector<char> minn(x.size());
  minn[x.size() - 1] = x[x.size() - 1];
  for (int i = x.size() - 2; i >= 0; i--) {
    minn[i] = min(minn[i + 1], x[i]);
  }
  for (int i = 0; i < x.size(); i++) {
    while (!st.empty() && st.top() <= minn[i]) {
      ans.push_back(st.top());
      st.pop();
    }
    st.push(x[i]);
  }
  while (!st.empty()) {
    ans.push_back(st.top());
    st.pop();
  }
  cout << ans;
}
