#include<stdio.h>
#include<assert.h>
#include<string.h>
#include<vector>
#include<set>
#include<algorithm>
#include<iostream>

using namespace std;

typedef long long int ll;

#define mp	make_pair
#define pb push_back

void solve()
{
	vector<int> input;
	int N,diff;
	scanf("%d%d",&N,&diff);
	assert( diff >= 0 && diff<=100000);
	for(int i=0;i<N;i++){
		int x;
		scanf("%d",&x);
		input.pb(x);
	}
	sort(input.begin(),input.end());
	ll sum = 0;
	for(int i=N-1;i>0;i--){
		if( (input[i] - input[i-1]) < diff){
			sum += input[i] + input[i-1];
			i--;
		}
	}
	printf("%lld\n",sum);
}

int main()
{
	int T;
	cin>>T;
	for(int i=1;i<=T;i++){
		solve();
	}
	return 0;
}