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 s;
  cin >> s;
  stack<char> st;
  int n = s.length();
  vector<char> mn(n);
  mn[n - 1] = s.back();
  for (int i = n - 2; i >= 0; i--) mn[i] = min(s[i], mn[i + 1]);
  string res = "";
  for (int i = 0; i < n; i++) {
    if (i == n - 1) {
      while (!st.empty() && st.top() <= s[i]) {
        res += st.top();
        st.pop();
      }
      st.push(s[i]);
      continue;
    }
    while (!st.empty() && st.top() <= mn[i]) {
      res += st.top();
      st.pop();
    }
    if (s[i] == mn[i])
      res += s[i];
    else
      st.push(s[i]);
  }
  while (!st.empty()) {
    res += st.top();
    st.pop();
  }
  cout << res << "\n";
  return 0;
}
