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 A {
  	static FastReader sc=null;
  	
  	public static void main(String[] args) {
  		sc=new FastReader();
  		int t=sc.nextInt();
  		PrintWriter out=new PrintWriter(System.out);
  		while(t-->0) {
  			int n=sc.nextInt(),k=sc.nextInt(),
  					m=Integer.numberOfTrailingZeros(Integer.highestOneBit(2*n+1)),nax=(1<<m);
  			int a[]=sc.readArray(n);
  			Pair p[]=new Pair[nax];
  			for(int i=0;i<nax;i++)p[i]=new Pair(-1,-1);
  			for(int i=0;i<n;i++)p[a[i]]=combine(p[a[i]],new Pair(i,-1));
  			
  			//for this ai|aj what is the maximum we can get
  			//the or value will be k if we or k with any of its submasks
  			
  			for(int i=0;i<m;i++) {
  				for(int mask=0;mask<nax;mask++) {
  					if((mask&(1<<i))>0) {
  						p[mask]=combine(p[mask],p[mask^(1<<i)]);
  					}
  				}
  			}
  			long ans=Long.MIN_VALUE;
  			for(int mask=0;mask<nax;mask++) {
  				if(p[mask].l!=-1) {
  					ans=Math.max(ans, get(mask,p[mask],k));
  				}
  			}
  			out.println(ans);
  			
  		}
  		out.close();
  		
  		
  		
  		
  	}
  	static long get(int mask,Pair p,int k) {
  		return (p.l+1)*1L*(p.r+1) - k*1L*mask;
  	}
  	static class Pair{
  		int l,r;
  		Pair(int l,int r){
  			this.l=l;
  			this.r=r;
  		}
  	}
  	static Pair combine(Pair a,Pair b) {
  		int v[]= {a.l,a.r,b.l,b.r};
  		Arrays.sort(v);
  		return new Pair(v[2],v[3]);
  	}
  	
  	
  	static int[] ruffleSort(int a[]) {
  		ArrayList<Integer> al=new ArrayList<>();
  		for(int i:a)al.add(i);
  		Collections.sort(al);
  		for(int i=0;i<a.length;i++)a[i]=al.get(i);
  		return a;
  	}
  	static void print(int a[]) {
  		for(int e:a) {
  			System.out.print(e+" ");
  		}
  		System.out.println();
  	}
  	
  	static class FastReader{
  		
  		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
  		StringTokenizer st=new StringTokenizer("");
  		
  		String next() {
  			while(!st.hasMoreTokens())
  				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());
  		}
  		
  		int[] readArray(int n) {
  			int a[]=new int[n];
  			for(int i=0;i<n;i++)a[i]=sc.nextInt();
  			return a;
  		}
  	}
  }
  
  
  
  
  
  
  