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.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.StringTokenizer;
  
  public class B implements Runnable {
  
  	public static void main(String[] args) throws Exception {
  
  		new Thread(null, new B(), "SwapnilGanguly", 1 << 24).start();
  	}
  
  	public void run() {
  
  		SwapScanner sc = new SwapScanner();
  		PrintWriter pr = new PrintWriter(System.out);
  
  		int T = sc.nextInt();
  
  		// Brute Force
  
  		while (T-- > 0) {
  
  			int n = sc.nextInt(), k = sc.nextInt();
  			long[] ar = new long[n + 1];
  
  			for (int i = 1; i <= n; i++)
  				ar[i] = sc.nextLong();
  
  			long ans = Integer.MIN_VALUE;
  			long start = Math.max(1, n - 200);
  
  			for (long i = start; i <= n; i++) {
  				for (long j = i + 1; j <= n; j++) {
  
  					long temp = (i * j) - (k * (ar[(int) i] | ar[(int) j]));
  					ans = Math.max(ans, temp);
  				}
  			}
  
  			pr.println(ans);
  		}
  
  		pr.close();
  	}
  
  	public static void sort(int[] a) {
  
  		ArrayList<Integer> l = new ArrayList<>();
  
  		for (int i : a)
  			l.add(i);
  
  		Collections.sort(l);
  
  		for (int i = 0; i < a.length; i++)
  			a[i] = l.get(i);
  	}
  
  	public static class SwapScanner {
  
  		BufferedReader br;
  		StringTokenizer st;
  
  		public SwapScanner() {
  
  			br = new BufferedReader(new InputStreamReader(System.in));
  		}
  
  		String next() {
  
  			while (st == null || !st.hasMoreElements()) {
  
  				try {
  
  					st = new StringTokenizer(br.readLine());
  				}
  
  				catch (IOException e) {
  
  					e.printStackTrace();
  				}
  			}
  
  			return st.nextToken();
  		}
  
  		int nextInt() {
  
  			return Integer.parseInt(next());
  		}
  
  		long nextLong() {
  
  			return Long.parseLong(next());
  		}
  
  		double nextDouble() {
  
  			return Double.parseDouble(next());
  		}
  
  		String nextLine() {
  
  			String str = "";
  
  			try {
  
  				str = br.readLine();
  			}
  
  			catch (IOException e) {
  
  				e.printStackTrace();
  			}
  
  			return str;
  		}
  
  		int[] readArray(int n) {
  
  			int[] ar = new int[n];
  
  			for (int i = 0; i < n; i++)
  				ar[i] = nextInt();
  
  			return ar;
  		}
  	}
  }