mod = 1000000007
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    N, T = map(int, input().split())
    A = list(map(int, input().split()))

    X = {T: 0}
    for a in A:
        X_new = {}
        for x in X:
            x_and = x & a
            x_or = x | a
            if x_and not in X_new:
                X_new[x_and] = X[x] + x - x_and
            else:
                X_new[x_and] = max(X_new[x_and], X[x] + x - x_and)
            if x_or not in X_new:
                X_new[x_or] = X[x] + x_or - x
            else:
                X_new[x_or] = max(X_new[x_or], X[x] + x_or - x)
        X = X_new
        #print(X)
    ans = 0
    for x in X:
        ans = max(ans, X[x])
    print(ans)


if __name__ == '__main__':
    main()