//wtrl,everybody hangbeat me
#include<bits/stdc++.h>
/*#include<iostream>
#include<string>
#include<cmath>
#include<cstdio>
#include<cctype>
#include<cstring>
#include<iomanip>
#include<cstdlib>
#include<ctime>
#include<set>
#include<map>
#include<utility>
#include<queue>
#include<vector>
#include<stack>
#include<sstream>
#include<algorithm>*/
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<pii> vii;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<vi> vvi;
typedef pair<ll,ll> pll;
/*=====================================================================*/
#define pb push_back
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(s) (s).begin(),(s).end()
#define repd(i,n) for(int i=n-1;i>=0;i--)
#define forn(i,p,n) for(int i=p;i<=n;i++)
#define ford(i,p,n) for(int i=n;i>=p;i--)
#define foreach(i,c) for(__typeof(c.begin())i=(c.begin());i!=(c).end();++i)
#define INF 1e9
#define PI acos(-1)
/*=====================================================================*/
string int_to_string(ll n)
{
    string s="";
    while(n)
    {
        ll now=n%10;
        s+=now+'0';
        n/=10;
    }
    reverse(s.begin(),s.end());
    return s;
}
ll string_to_int(string s)
{
    ll n=0;
    rep(i,s.size())
    {
        n*=10;
        n+=s[i]-'0';
    }
    return n;
}
/*======================================================================*/
const int dx[]={-1,0,1,0};
const int dy[]={0,-1,0,1};
const int month[2][12]={{31,28,31,30,31,30,31,31,30,31,30,31},{31,29,31,30,31,30,31,31,30,31,30,31}};
//think twice,code once
//think once,debug forever
int a[100010];
int n,k;
bool check(int mid)
{
    //mp.clear();
    int low=a[1]-k;
    //cout<<mid<<" ";
    mid--;
    forn(i,2,n)
    {
        //cout<<i<<" "<<low<<endl;
        if(low<a[i]-k)
        {
            low=a[i]-k;
            mid--;
        }
        else
        {
            if(low+1>a[i]+k)
            {
                continue;
            }
            low++;
            //mp[low]=1;
            mid--;
        }
        //cout<<i<<" "<<low<<endl;
    }
    //cout<<mid<<endl;
    return mid<=0;
}
void solve()
{
    cin>>n>>k;
    forn(i,1,n)
    {
        cin>>a[i];
    }
    sort(a+1,a+1+n);
    int l=0,r=n,ans=0;
    while(l<r)
    {
        int mid=(l+r)>>1;
        if(check(mid))
        {
            ans=mid;
            l=mid+1;
        }
        else
        {
            r=mid-1;
        }
    }
    ford(i,ans-2,ans+2)
    {
        if(check(i))
        {
            cout<<i<<endl;
            return;
        }
    }
}
/*======================================================================*/
signed main()
{
    std::ios::sync_with_stdio(false);
  /*
    freopen("input.txt","r",stdin);
    freopen("output.txt","w",stdout);
  */
  /*====================================================================*/
  int t=1;
  cin>>t;
  while(t--)
  {
      solve();
  }
  return 0;
}
/*
注意数组越界，vector长度为0的时候循环会RE
注意输入顺序
注意循环时int*int爆ll
注意答案存爆ll
存答案用string过慢，最好直接输出或者用vector<char>
memset是O(n)
*/