description: You are given n integers a_1, a_2, …, a_n and an integer k. Find the maximum value of i ⋅ j - k ⋅ (a_i | a_j) over all pairs (i, j) of integers with 1 ≤ i < j ≤ n. Here, | is the [bitwise OR operator](https://en.wikipedia.org/wiki/Bitwise_operation#OR).
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 10 000) — the number of test cases.
  
  The first line of each test case contains two integers n (2 ≤ n ≤ 10^5) and k (1 ≤ k ≤ min(n, 100)).
  
  The second line of each test case contains n integers a_1, a_2, …, a_n (0 ≤ a_i ≤ n).
  
  It is guaranteed that the sum of n over all test cases doesn't exceed 3 ⋅ 10^5.
  
  Output
  
  For each test case, print a single integer — the maximum possible value of i ⋅ j - k ⋅ (a_i | a_j).
  
  Example
  
  Input
  
  
  4
  3 3
  1 1 3
  2 2
  1 2
  4 3
  0 1 2 3
  6 6
  3 2 0 0 5 6
  
  
  Output
  
  
  -1
  -4
  3
  12
  
  Note
  
  Let f(i, j) = i ⋅ j - k ⋅ (a_i | a_j).
  
  In the first test case, 
  
    * f(1, 2) = 1 ⋅ 2 - k ⋅ (a_1 | a_2) = 2 - 3 ⋅ (1 | 1) = -1. 
    * f(1, 3) = 1 ⋅ 3 - k ⋅ (a_1 | a_3) = 3 - 3 ⋅ (1 | 3) = -6. 
    * f(2, 3) = 2 ⋅ 3 - k ⋅ (a_2 | a_3) = 6 - 3 ⋅ (1 | 3) = -3. 
  
  
  
  So the maximum is f(1, 2) = -1.
  
  In the fourth test case, the maximum is f(3, 4) = 12.
solution: import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.*;
  
  public class Main implements Runnable {
      int n, m, k;
      static boolean use_n_tests =  true;
      long mod = 1_000_000_007;
      Map<Integer, Map<Integer, Integer>> dp;
  
      void solve(FastScanner in, PrintWriter out, int testNumber) {
          n = in.nextInt();
          k = in.nextInt();
          Integer[] a = in.nextArray2(n);
          long ans = produceAns(0, a);
          for (int i = 100; i < n; i++) {
              for (int j = i - 100; j < i; j++) {
                  int idi = i + 1;
                  int idk = j + 1;
                  ans = Math.max(ans, idi * 1l * idk - this.k * 1l * (a[i] | a[j]));
              }
          }
          out.println(ans);
  
      }
  
      long produceAns(int i, Integer[] a) {
          long ans = Long.MIN_VALUE;
          for (int j = i; j < i + 100 && j < a.length; j++) {
              int idi = j + 1;
              for (int k = j + 1; k < i + 100 && k < a.length; k++) {
                  int idk = k + 1;
                  ans = Math.max(ans, idi * 1l * idk - this.k * 1l * (a[j] | a[k]));
              }
          }
          return ans;
      }
  
      class Pt {
          Pt(int x, int y) {
              this.x = x;
              this.y = y;
          }
          int x, y;
          int getX() {
              return x;
          }
  
          int getY() {
              return y;
          }
      }
  
      // ****************************** template code ***********
  
      void swap(Integer[] a, int i, int j) {
          Integer tmp = a[i];
          a[i] = a[j];
          a[j] = tmp;
      }
  
      long manhDist(long x, long y, long x1, long y1) {
          return Math.abs(x - x1) + Math.abs(y - y1);
      }
  
      double dist(double x, double y, double x1, double y1) {
          return Math.sqrt(Math.pow(x - x1, 2.0) + Math.pow(y - y1, 2.0));
      }
  
      public static class FW {
          public static void add(long[] t, int i, long value) {
              for (; i < t.length; i |= i + 1)
                  t[i] += value;
          }
          public static long sum(long[] t, int i) {
              long res = 0;
              for (; i >= 0; i = (i & (i + 1)) - 1)
                  res += t[i];
              return res;
          }
  
          public static void add(long[] t, int a, int b, long value) {
              add(t, a, value);
              add(t, b + 1, -value);
          }
      }
  
      int sign(int a) {
          if (a < 0) {
              return -1;
          }
          return 1;
      }
  
      long binpow(long a, int b) {
          long res = 1;
          while (b != 0) {
              if (b % 2 == 0) {
                  b /= 2;
                  a *= a;
                  a %= mod;
              }
  
              b--;
              res *= a;
              res %= mod;
          }
          return res;
      }
  
      List<Integer> getGidits(long n) {
          List<Integer> res = new ArrayList<>();
          while (n != 0) {
              res.add((int) (n % 10L));
              n /= 10;
          }
          return res;
      }
  
      List<Integer> generatePrimes(int n) {
          List<Integer> res = new ArrayList<>();
          boolean[] sieve = new boolean[n + 1];
          for (int i = 2; i <= n; i++) {
              if (!sieve[i]) {
                  res.add(i);
              }
              if ((long) i * i <= n) {
                  for (int j = i * i; j <= n; j += i) {
                      sieve[j] = true;
                  }
              }
          }
          return res;
      }
  
      int[] ask(int l) {
          System.out.printf("? %d\n", l);
          System.out.flush();
          return in.nextArray(n);
      }
  
      static int stack_size = 1 << 27;
  
      static class Coeff {
          long mod;
          long[][] C;
          long[] fact;
          boolean cycleWay = false;
  
          Coeff(int n, long mod) {
              this.mod = mod;
              fact = new long[n + 1];
              fact[0] = 1;
              for (int i = 1; i <= n; i++) {
                  fact[i] = i;
                  fact[i] %= mod;
                  fact[i] *= fact[i - 1];
                  fact[i] %= mod;
              }
          }
  
          Coeff(int n, int m, long mod) {
              // n > m
              cycleWay = true;
              this.mod = mod;
              C = new long[n + 1][m + 1];
              for (int i = 0; i <= n; i++) {
                  for (int j = 0; j <= Math.min(i, m); j++) {
                      if (j == 0 || j == i) {
                          C[i][j] = 1;
                      } else {
                          C[i][j] = C[i - 1][j - 1] + C[i - 1][j];
                          C[i][j] %= mod;
                      }
                  }
              }
          }
  
          public long C(int n, int m) {
              if (cycleWay) {
                  return C[n][m];
              }
              return fC(n, m);
          }
  
          private long fC(int n, int m) {
              return (fact[n] * inv(fact[n - m] * fact[m] % mod)) % mod;
          }
  
          private long inv(long r) {
              if (r == 1)
                  return 1;
              return ((mod - mod / r) * inv(mod % r)) % mod;
          }
      }
  
      class Pair {
          int first;
          long second;
  
          Pair(int f, long s) {
              first = f;
              second = s;
          }
  
          public int getFirst() {
              return first;
          }
  
          public long getSecond() {
              return second;
          }
      }
  
      class MultisetTree<T> {
          int size = 0;
  
          TreeMap<T, Integer> mp = new TreeMap<>();
  
          void add(T x) {
              mp.merge(x, 1, Integer::sum);
              size++;
          }
  
          void remove(T x) {
              if (mp.containsKey(x)) {
                  mp.merge(x, -1, Integer::sum);
                  if (mp.get(x) == 0) {
                      mp.remove(x);
                  }
                  size--;
              }
          }
  
          boolean contains(T x) {
              return mp.containsKey(x);
          }
  
          T greatest() {
              return mp.lastKey();
          }
  
          T smallest() {
              return mp.firstKey();
          }
  
          int size() {
              return size;
          }
  
          int diffSize() {
              return mp.size();
          }
      }
  
      class Multiset<T> {
          int size = 0;
  
          Map<T, Integer> mp = new HashMap<>();
  
          void add(T x) {
              mp.merge(x, 1, Integer::sum);
              size++;
          }
  
          boolean contains(T x) {
              return mp.containsKey(x);
          }
  
          void remove(T x) {
              if (mp.containsKey(x)) {
                  mp.merge(x, -1, Integer::sum);
                  if (mp.get(x) == 0) {
                      mp.remove(x);
                  }
                  size--;
              }
          }
  
          int size() {
              return size;
          }
  
          int diffSize() {
              return mp.size();
          }
      }
  
      static class Range {
          int l, r;
          int id;
  
          public int getL() {
              return l;
          }
  
          public int getR() {
              return r;
          }
  
          public Range(int l, int r, int id) {
              this.l = l;
              this.r = r;
              this.id = id;
          }
      }
  
      static class Array {
          static Range[] readRanges(int n, FastScanner in) {
              Range[] result = new Range[n];
              for (int i = 0; i < n; i++) {
                  result[i] = new Range(in.nextInt(), in.nextInt(), i);
              }
              return result;
          }
  
          static List<List<Integer>> intInit2D(int n) {
              List<List<Integer>> res = new ArrayList<>();
              for (int i = 0; i < n; i++) {
                  res.add(new ArrayList<>());
              }
              return res;
          }
  
          static boolean isSorted(Integer[] a) {
              for (int i = 0; i < a.length - 1; i++) {
                  if (a[i] > a[i + 1]) {
                      return false;
                  }
              }
              return true;
          }
  
          static public long sum(int[] a) {
              long sum = 0;
              for (int x : a) {
                  sum += x;
              }
              return sum;
          }
  
          static public long sum(long[] a) {
              long sum = 0;
              for (long x : a) {
                  sum += x;
              }
              return sum;
          }
  
          static public long sum(Integer[] a) {
              long sum = 0;
              for (int x : a) {
                  sum += x;
              }
              return sum;
          }
  
          static public int min(Integer[] a) {
              int mn = Integer.MAX_VALUE;
              for (int x : a) {
                  mn = Math.min(mn, x);
              }
              return mn;
          }
  
          static public int min(int[] a) {
              int mn = Integer.MAX_VALUE;
              for (int x : a) {
                  mn = Math.min(mn, x);
              }
              return mn;
          }
  
          static public int max(Integer[] a) {
              int mx = Integer.MIN_VALUE;
              for (int x : a) {
                  mx = Math.max(mx, x);
              }
              return mx;
          }
  
          static public int max(int[] a) {
              int mx = Integer.MIN_VALUE;
              for (int x : a) {
                  mx = Math.max(mx, x);
              }
              return mx;
          }
  
          static public int[] readint(int n, FastScanner in) {
              int[] out = new int[n];
              for (int i = 0; i < out.length; i++) {
                  out[i] = in.nextInt();
              }
              return out;
          }
      }
  
      class Graph {
          List<List<Integer>> graph;
  
          Graph(int n) {
              create(n);
          }
  
          private void create(int n) {
              List<List<Integer>> graph = new ArrayList<>();
              for (int i = 0; i < n; i++) {
                  graph.add(new ArrayList<>());
              }
              this.graph = graph;
          }
  
          void read(int m, FastScanner in) {
              for (int i = 0; i < m; i++) {
                  int v = in.nextInt() - 1;
                  int u = in.nextInt() - 1;
                  graph.get(v).add(u);
              }
          }
  
          void readBi(int m, FastScanner in) {
              for (int i = 0; i < m; i++) {
                  int v = in.nextInt() - 1;
                  int u = in.nextInt() - 1;
                  graph.get(v).add(u);
                  graph.get(u).add(v);
              }
          }
      }
  
      class FastScanner {
          BufferedReader br;
          StringTokenizer st;
  
          public FastScanner(InputStream io) {
              br = new BufferedReader(new InputStreamReader(io));
          }
  
          public String line() {
              String result = "";
              try {
                  result = br.readLine();
              } catch (IOException e) {
                  e.printStackTrace();
              }
              return result;
          }
  
          public String next() {
              while (st == null || !st.hasMoreElements()) {
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
              return st.nextToken();
          }
  
          public char[] nextc() {
              return next().toCharArray();
          }
  
          public int nextInt() {
              return Integer.parseInt(next());
          }
  
          public int[] nextArray(int n) {
              int[] res = new int[n];
              for (int i = 0; i < n; i++) {
                  res[i] = in.nextInt();
              }
              return res;
          }
  
          public long[] nextArrayL(int n) {
              long[] res = new long[n];
              for (int i = 0; i < n; i++) {
                  res[i] = in.nextLong();
              }
              return res;
          }
  
          public Long[] nextArrayL2(int n) {
              Long[] res = new Long[n];
              for (int i = 0; i < n; i++) {
                  res[i] = in.nextLong();
              }
              return res;
          }
  
  
          public Integer[] nextArray2(int n) {
              Integer[] res = new Integer[n];
              for (int i = 0; i < n; i++) {
                  res[i] = in.nextInt();
              }
              return res;
          }
  
          public long nextLong() {
              return Long.parseLong(next());
          }
  
      }
  
      void run_t_tests() {
          int t = in.nextInt();
          int i = 0;
          while (t-- > 0) {
              solve(in, out, i++);
          }
      }
  
      void run_one() {
          solve(in, out, -1);
      }
  
      @Override
      public void run() {
          in = new FastScanner(System.in);
          out = new PrintWriter(System.out);
          if (use_n_tests) {
              run_t_tests();
          } else {
              run_one();
          }
          out.close();
      }
  
      static FastScanner in;
      static PrintWriter out;
  
      public static void main(String[] args) throws InterruptedException {
          Thread thread = new Thread(null, new Main(), "", stack_size);
          thread.start();
          thread.join();
      }
  }