This is an easier version of the problem with smaller constraints.

Korney Korneevich dag up an array $$$a$$$ of length $$$n$$$. Korney Korneevich has recently read about the operation bitwise XOR, so he wished to experiment with it. For this purpose, he decided to find all integers $$$x \ge 0$$$ such that there exists an increasing subsequence of the array $$$a$$$, in which the bitwise XOR of numbers is equal to $$$x$$$.

It didn't take a long time for Korney Korneevich to find all such $$$x$$$, and he wants to check his result. That's why he asked you to solve this problem!

A sequence $$$s$$$ is a subsequence of a sequence $$$b$$$ if $$$s$$$ can be obtained from $$$b$$$ by deletion of several (possibly, zero or all) elements.

A sequence $$$s_1, s_2, \ldots , s_m$$$ is called increasing if $$$s_1 \lt s_2 \lt \ldots \lt s_m$$$.

Input

The first line contains a single integer $$$n$$$ ($$$1 \le n \le 10^5$$$).

The second line contains $$$n$$$ integers $$$a_1, a_2, \ldots, a_n$$$ ($$$0 \le a_i \le 500$$$) — the elements of the array $$$a$$$.

Output

In the first line print a single integer $$$k$$$ — the number of found $$$x$$$ values.

In the second line print $$$k$$$ integers in increasing order $$$x_1, x_2, \ldots x_k$$$ ($$$0 \le x_1 \lt \ldots \lt x_k$$$) — found $$$x$$$ values.

Note

In the first test case:

To get value $$$x = 0$$$ it is possible to choose and empty subsequence
To get value $$$x = 2$$$ it is possible to choose a subsequence $$$[2]$$$
To get value $$$x = 4$$$ it is possible to choose a subsequence $$$[4]$$$
To get value $$$x = 6$$$ it is possible to choose a subsequence $$$[2, 4]$$$

Korney Korneevich and XOR (easy version)

Examples