import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.BufferedWriter;
import java.io.Writer;
import java.io.OutputStreamWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author prakharjain
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        OutputWriter out = new OutputWriter(outputStream);
        DXXOR solver = new DXXOR();
        solver.solve(1, in, out);
        out.close();
    }

    static class DXXOR {
        public void solve(int testNumber, InputReader in, OutputWriter out) {
            int n = in.nextInt();

            long k = in.nextLong();


            long[] a = in.nla(n);

            long[] pd = new long[40];

            for (int i = 0; i < 40; i++) {
                for (int j = 0; j < n; j++) {
                    if ((a[j] & (1l << i)) != 0) {
                        pd[i]++;
                    }
                }
            }

            long[][] dp = new long[41][2];

            boolean fd = false;
            for (int i = 39; i >= 0; i--) {
                long val = (1l << i);

                //tight
                if (((1l << i) & k) == 0) {
                    dp[i][1] = dp[i + 1][1] + pd[i] * (1l << i);
                } else {
                    dp[i][1] = dp[i + 1][1] + (n - pd[i]) * (1l << i);
                }

                //loose
                if (((1l << i) & k) != 0) {
                    dp[i][0] = dp[i + 1][1] + pd[i] * val;
                    if (fd)
                        dp[i][0] = Math.max(dp[i][0],
                                dp[i + 1][0] + Math.max(pd[i], n - pd[i]) * val);
                } else if (fd) {
                    dp[i][0] = dp[i + 1][0] + Math.max(pd[i], n - pd[i]) * val;
                }

                if ((k & (1l << i)) != 0) {
                    fd = true;
                }
            }

            out.println(Math.max(dp[0][0], dp[0][1]));
        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private InputReader.SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public static boolean isWhitespace(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public int read() {
            if (numChars == -1) {
                throw new InputMismatchException();
            }
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;
            do {
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public boolean isSpaceChar(int c) {
            if (filter != null) {
                return filter.isSpaceChar(c);
            }
            return isWhitespace(c);
        }

        public long[] nla(int n) {
            return nextLongArray(n);
        }

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

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        }

    }

    static class OutputWriter {
        private final PrintWriter writer;

        public OutputWriter(OutputStream outputStream) {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
        }

        public OutputWriter(Writer writer) {
            this.writer = new PrintWriter(writer);
        }

        public void close() {
            writer.close();
        }

        public void println(long i) {
            writer.println(i);
        }

    }
}



Measured memory_bytes: 26756