import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int t = sc.nextInt();
        ArrayList<HashMap<Integer, Long>> dp = new ArrayList<>();
        for (int i = 0; i <= n; i++) {
            dp.add(new HashMap<>());
        }
        dp.get(0).put(t, 0L);
        for (int i = 1; i <= n; i++) {
            int a = sc.nextInt();
            for (Map.Entry<Integer, Long> entry : dp.get(i - 1).entrySet()) {
                int next1 = (entry.getKey() & a);
                long value1 = entry.getValue() + Math.abs(next1 - entry.getKey());
                if (!dp.get(i).containsKey(next1) || dp.get(i).get(next1) < value1) {
                    dp.get(i).put(next1, value1);
                }
                int next2 = (entry.getKey() | a);
                long value2 = entry.getValue() + Math.abs(next2 - entry.getKey());
                if (!dp.get(i).containsKey(next2) || dp.get(i).get(next2) < value2) {
                    dp.get(i).put(next2, value2);
                }
            }
        }
        long max = 0;
        for (long x : dp.get(n).values()) {
            max = Math.max(max, x);
        }
        System.out.println(max);
    }
}