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;
char s[100001], an[100001], mn[100001];
int main() {
  scanf("%s", s);
  int n = strlen(s);
  mn[n] = 'z' + 1;
  for (int i = n - 1; i >= 0; --i) mn[i] = min(mn[i + 1], s[i]);
  stack<char> st;
  int j = 0;
  for (int i = 0; i < (int)(n); ++i) {
    st.push(s[i]);
    while (!st.empty() && st.top() <= mn[i + 1]) an[j++] = st.top(), st.pop();
  }
  printf("%s\n", an);
}
