import sys

# sys.setrecursionlimit(200005)
# sys.set_int_max_str_digits(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
# inf = -1-(-1 << 31)
inf = -1-(-1 << 62)

# md = 10**9+7
md = 998244353

from collections import defaultdict
from random import randrange

class Defaultdict(defaultdict):
    def __init__(self, df):
        super().__init__(df)
        self.x = randrange(1 << 31)

    def __setitem__(self, key, value):
        super().__setitem__(key ^ self.x, value)

    def __getitem__(self, item):
        return super().__getitem__(item ^ self.x)

    def __missing__(self, key):
        return super().__missing__(key ^ self.x)

    def __iter__(self):
        for a in super().__iter__(): yield a ^ self.x

    def __contains__(self, item):
        return super().__contains__(item ^ self.x)

    def __delitem__(self, key):
        super().__delitem__(key ^ self.x)

    def items(self):
        return [(k ^ self.x, v) for k, v in super().items()]

class Set(set):
    def __init__(self):
        super().__init__()
        self.x = randrange(1 << 31)

    def add(self, a):
        super().add(a ^ self.x)

    def pop(self):
        return super().pop() ^ self.x

    def remove(self, a):
        super().remove(a ^ self.x)

    def discard(self, a):
        super().discard(a ^ self.x)

    def __contains__(self, item):
        return super().__contains__(item ^ self.x)

    def __iter__(self):
        for a in super().__iter__(): yield a ^ self.x

def chmax(t, nt):
    ndp[nt] = max(ndp[nt], dp[t]+abs(nt-t))

n, t = LI()
aa = LI()
dp = Defaultdict(int)
dp[t] = 0
for a in aa:
    ndp = Defaultdict(int)
    for t in dp:
        chmax(t,t|a)
        chmax(t,t&a)
    dp=ndp

print(max(dp.values()))