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.*;
  import java.util.*;
  
  public class B {
  
  	public static void main(String[] args) {
  		
  		FastReader f = new FastReader();
  		StringBuffer sb=new StringBuffer();
  		int test=f.nextInt();
  		out:
  		while(test-->0)
  		{			
  			int n=f.nextInt();
  			int k=f.nextInt();
  					
  			int a[]=new int[n];
  			for(int i=0;i<n;i++)
  				a[i]=f.nextInt();
  			long max=Long.MIN_VALUE;
  			for(int i=n-1;i>=Math.max(0,n-200);i--)
  			{
  				for(int j=i-1;j>=Math.max(0,n-200);j--)
  					max=Math.max(max,((long)(i+1)*(j+1) - (long)k*(a[i]|a[j])));
  			}
  			sb.append(max+"\n");
  		}
  		System.out.println(sb);
  	}
  	
  	static class FastReader 
  	{ 
  	    BufferedReader br; 
  	    StringTokenizer st; 
   
  	    public FastReader() {
  	    	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; 
  	    } 
  	} 
  }
  