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;
stack<char> st;
string s, ans = "";
char mn[111111];
long long n;
int main() {
  cin >> s;
  n = s.size();
  mn[n - 1] = s[n - 1];
  for (int i = n - 2; i >= 0; i--) {
    mn[i] = min(mn[i + 1], s[i]);
  }
  for (int i = 0; i < n;) {
    if (st.empty()) {
      st.push(s[i]);
      i++;
    } else if (st.top() <= mn[i]) {
      ans += st.top();
      st.pop();
    } else {
      st.push(s[i]);
      i++;
    }
  }
  while (!st.empty()) {
    ans += st.top();
    st.pop();
  }
  cout << ans;
  return 0;
}
