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](https://en.wikipedia.org/wiki/Bitwise_operation#XOR), so he wished to experiment with it. For this purpose, he decided to find all integers x ≥ 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, … , s_m is called increasing if s_1 < s_2 < … < s_m.

Input

The first line contains a single integer n (1 ≤ n ≤ 10^5).

The second line contains n integers a_1, a_2, …, a_n (0 ≤ a_i ≤ 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, … x_k (0 ≤ x_1 < … < x_k) — found x values.

Examples

Input


4
4 2 2 4


Output


4
0 2 4 6 


Input


8
1 0 1 7 12 5 3 2


Output


12
0 1 2 3 4 5 6 7 10 11 12 13 

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] 
import sys
from collections import defaultdict
from io import BytesIO, IOBase
import string


class FastIO(IOBase):
    newlines = 0

    def __init__(self, file):
        import os
        self.os = os
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = "x" in file.mode or "r" not in file.mode
        self.write = self.buffer.write if self.writable else None
        self.BUFSIZE = 8192

    def read(self):
        while True:
            b = self.os.read(self._fd, max(self.os.fstat(self._fd).st_size, self.BUFSIZE))
            if not b:
                break
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines = 0
        return self.buffer.read()

    def readline(self):
        while self.newlines == 0:
            b = self.os.read(self._fd, max(self.os.fstat(self._fd).st_size, self.BUFSIZE))
            self.newlines = b.count(b"\n") + (not b)
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines -= 1
        return self.buffer.readline()

    def flush(self):
        if self.writable:
            self.os.write(self._fd, self.buffer.getvalue())
            self.buffer.truncate(0), self.buffer.seek(0)


class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        self.write = lambda s: self.buffer.write(s.encode("ascii"))
        self.read = lambda: self.buffer.read().decode("ascii")
        self.readline = lambda: self.buffer.readline().decode("ascii")


sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)
input = lambda: sys.stdin.readline().rstrip("\r\n")


def get_int():
    return int(input())


def get_ints():
    return list(map(int, input().split(' ')))


def get_int_grid(n):
    return [get_ints() for _ in range(n)]


def get_str():
    return input().strip()


def get_strs():
    return get_str().split(' ')


def flat_list(arr):
    return [item for subarr in arr for item in subarr]


def yes_no(b):
    if b:
        return "YES"
    else:
        return "NO"


def binary_search(good, left, right, delta=1, right_true=False):
    """
    Performs binary search
    ----------
    Parameters
    ----------
    :param good: Function used to perform the binary search
    :param left: Starting value of left limit
    :param right: Starting value of the right limit
    :param delta: Margin of error, defaults value of 1 for integer binary search
    :param right_true: Boolean, for whether the right limit is the true invariant
    :return: Returns the most extremal value interval [left, right] which is good function evaluates to True,
            alternatively returns False if no such value found
    """

    limits = [left, right]
    while limits[1] - limits[0] > delta:
        if delta == 1:
            mid = sum(limits) // 2
        else:
            mid = sum(limits) / 2
        if good(mid):
            limits[int(right_true)] = mid
        else:
            limits[int(~right_true)] = mid
    if good(limits[int(right_true)]):
        return limits[int(right_true)]
    else:
        return False


def prefix_sums(a):
    p = [0]
    for x in a:
        p.append(p[-1] + x)
    return p




def solve_f():
    n = get_int()
    a = get_ints()
    lf = [501] * 1024
    lf[0] = -1
    for x in a:
        tmp = lf[:]
        for i in range(1024):
            if x > lf[i]:
                tmp[i ^ x] = min(tmp[i ^ x], x)
        lf = tmp[:]
    ans = [i for i in range(1024) if lf[i] < 501]
    return ans


ans = solve_f()
print(len(ans))
print(*ans)
