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.util.*;
  import java.io.*;
  public class B {
      static class Scan {
          private byte[] buf=new byte[1024];
          private int index;
          private InputStream in;
          private int total;
          public Scan()
          {
              in=System.in;
          }
          public int scan()throws IOException
          {
              if(total<0)
              throw new InputMismatchException();
              if(index>=total)
              {
                  index=0;
                  total=in.read(buf);
                  if(total<=0)
                  return -1;
              }
              return buf[index++];
          }
          public int scanInt()throws IOException
          {
              int integer=0;
              int n=scan();
              while(isWhiteSpace(n))
              n=scan();
              int neg=1;
              if(n=='-')
              {
                  neg=-1;
                  n=scan();
              }
              while(!isWhiteSpace(n))
              {
                  if(n>='0'&&n<='9')
                  {
                      integer*=10;
                      integer+=n-'0';
                      n=scan();
                  }
                  else throw new InputMismatchException();
              }
              return neg*integer;
          }
          public double scanDouble()throws IOException
          {
              double doub=0;
              int n=scan();
              while(isWhiteSpace(n))
              n=scan();
              int neg=1;
              if(n=='-')
              {
                  neg=-1;
                  n=scan();
              }
              while(!isWhiteSpace(n)&&n!='.')
              {
                  if(n>='0'&&n<='9')
                  {
                      doub*=10;
                      doub+=n-'0';
                      n=scan();
                  }
                  else throw new InputMismatchException();
              }
              if(n=='.')
              {
                  n=scan();
                  double temp=1;
                  while(!isWhiteSpace(n))
                  {
                      if(n>='0'&&n<='9')
                      {
                          temp/=10;
                          doub+=(n-'0')*temp;
                          n=scan();
                      }
                      else throw new InputMismatchException();
                  }
              }
              return doub*neg;
          }
          public String scanString()throws IOException
          {
              StringBuilder sb=new StringBuilder();
              int n=scan();
              while(isWhiteSpace(n))
              n=scan();
              while(!isWhiteSpace(n))
              {
                  sb.append((char)n);
                  n=scan();
              }
              return sb.toString();
          }
          private boolean isWhiteSpace(int n)
          {
              if(n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1)
              return true;
              return false;
          }
      }
      
      public static void sort(int arr[],int l,int r) {    //sort(arr,0,n-1);
          if(l==r) {
              return;
          }
          int mid=(l+r)/2;
          sort(arr,l,mid);
          sort(arr,mid+1,r);
          merge(arr,l,mid,mid+1,r);
      }
      public static void merge(int arr[],int l1,int r1,int l2,int r2) {
          int tmp[]=new int[r2-l1+1];
          int indx1=l1,indx2=l2;
          //sorting the two halves using a tmp array
          for(int i=0;i<tmp.length;i++) {
              if(indx1>r1) {
                  tmp[i]=arr[indx2];
                  indx2++;
                  continue;
              }
              if(indx2>r2) {
                  tmp[i]=arr[indx1];
                  indx1++;
                  continue;
              }
              if(arr[indx1]<arr[indx2]) {
                  tmp[i]=arr[indx1];
                  indx1++;
                  continue;
              }
              tmp[i]=arr[indx2];
              indx2++;
          }
          //Copying the elements of tmp into the main array
          for(int i=0,j=l1;i<tmp.length;i++,j++) {
              arr[j]=tmp[i];
          }
      }
      
      public static void sort(long arr[],int l,int r) {    //sort(arr,0,n-1);
          if(l==r) {
              return;
          }
          int mid=(l+r)/2;
          sort(arr,l,mid);
          sort(arr,mid+1,r);
          merge(arr,l,mid,mid+1,r);
      }
      public static void merge(long arr[],int l1,int r1,int l2,int r2) {
          long tmp[]=new long[r2-l1+1];
          int indx1=l1,indx2=l2;
          //sorting the two halves using a tmp array
          for(int i=0;i<tmp.length;i++) {
              if(indx1>r1) {
                  tmp[i]=arr[indx2];
                  indx2++;
                  continue;
              }
              if(indx2>r2) {
                  tmp[i]=arr[indx1];
                  indx1++;
                  continue;
              }
              if(arr[indx1]<arr[indx2]) {
                  tmp[i]=arr[indx1];
                  indx1++;
                  continue;
              }
              tmp[i]=arr[indx2];
              indx2++;
          }
          //Copying the elements of tmp into the main array
          for(int i=0,j=l1;i<tmp.length;i++,j++) {
              arr[j]=tmp[i];
          }
      }
      
      public static void main(String args[]) throws IOException {
          Scan input=new Scan();
          StringBuilder ans=new StringBuilder("");
          int test=input.scanInt();
          for(int tt=1;tt<=test;tt++) {
              int n=input.scanInt();
              long k=input.scanInt();
              long arr[]=new long[n];
              for(int i=0;i<n;i++) {
                  arr[i]=input.scanInt();
              }
              long fin=Long.MIN_VALUE;
              for(int i=Math.max(0,n-2*(int)k-1);i<n;i++) {
                  for(int j=i+1;j<n;j++) {
                      fin=Math.max(fin,((long)(i+1)*(long)(j+1))-(k*(arr[i]|arr[j])));
                  }
              }
              ans.append(fin+"\n");
          }
          System.out.println(ans);
      }
  }
  