import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.Random;
import java.util.StringTokenizer;

public final class Main{

    public static void main(String[] args) {
        final FastScanner fs = new FastScanner();
        final int n = fs.nextInt();
        final long k = fs.nextLong();
        final long[] arr = fs.nextLongArray(n);
        final int[] count = new int[Long.SIZE];
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < Long.SIZE; j++) {
                if ((arr[i] & (1L << j)) != 0) {
                    count[j]++;
                }
            }
        }
        long xor = 0;
        final long highestOneBit = Long.highestOneBit(k);
        final int idx = (int) (Math.log(highestOneBit) / Math.log(2));
        for (int i = idx; i >= 0; i--) {
            if (count[i] <= n / 2 && (xor | 1L << i) <= k) {
                xor |= 1L << i;
            }
        }
        long res = 0;
        for (int i = 0; i < n; i++) {
            res += xor ^ arr[i];
        }
        System.out.println(res);
    }

    static final class Utils {
        public static void shuffleSort(int[] arr) {
            shuffle(arr);
            Arrays.sort(arr);
        }

        public static void shuffleSort(long[] arr) {
            shuffle(arr);
            Arrays.sort(arr);
        }

        public static void shuffle(int[] arr) {
            final Random r = new Random();

            for (int i = 0; i <= arr.length - 2; i++) {
                final int j = i + r.nextInt(arr.length - i);
                swap(arr, i, j);
            }
        }

        public static void shuffle(long[] arr) {
            final Random r = new Random();

            for (int i = 0; i <= arr.length - 2; i++) {
                final int j = i + r.nextInt(arr.length - i);
                swap(arr, i, j);
            }
        }

        public static void swap(int[] arr, int i, int j) {
            final int t = arr[i];
            arr[i] = arr[j];
            arr[j] = t;
        }

        public static void swap(long[] arr, int i, int j) {
            final long t = arr[i];
            arr[i] = arr[j];
            arr[j] = t;
        }

        private Utils() {}
    }

    static class FastScanner {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer("");

        private String next() {
            while (!st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    //noinspection CallToPrintStackTrace
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        int[] nextIntArray(int n) {
            final int[] a = new int[n];
            for (int i = 0; i < n; i++) { a[i] = nextInt(); }
            return a;
        }

        long[] nextLongArray(int n) {
            final long[] a = new long[n];
            for (int i = 0; i < n; i++) { a[i] = nextLong(); }
            return a;
        }
    }
}


Measured memory_bytes: 47560