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;
const int oo = 100;
int i, j, k, n, m, s, t, ans;
char c[100005];
int a[100005];
int stk[100005];
int Min[100005];
int top;
int main() {
  scanf("%s", c + 1);
  n = strlen(c + 1);
  for (int i = 1; i <= n; i++) a[i] = c[i] - 'a';
  Min[n] = oo;
  for (int i = n - 1; i >= 1; i--) Min[i] = min(Min[i + 1], a[i + 1]);
  for (int i = 1; i <= n; i++) {
    stk[++top] = a[i];
    while (top && stk[top] <= Min[i]) putchar('a' + stk[top--]);
  }
  return 0;
}
