#include<bits/stdc++.h>
#define int long long
using namespace std;
const int maxn=4e5+10;
int T,n,A,B,a[maxn],sum[maxn],dp[maxn]; 
signed main(){
	scanf("%lld",&T);
	while(T--){
		scanf("%lld%lld%lld",&n,&A,&B);
		for(int i=1;i<=2*n;i++)
			scanf("%lld",&a[i]);
		sort(a+1,a+1+2*n);
		//for(int i=1;i<=2*n;i++) printf("a[%lld]=%lld\n",i,a[i]);
		for(int i=2;i<=2*n;i++)
			sum[i]=sum[i-2]+(a[i]-a[i-1]<=B);
		memset(dp,-0x3f,sizeof(dp));
		int INF=-dp[0];
		dp[0]=0;
		for(int i=2;i<=2*n;i+=2){
			int Sum=0;
			for(int j=i-1;j>=1;j-=2){
				if(a[i]-a[j]>A) break;
				if(j+2<=i) Sum+=(a[j+2]-a[j+1]<=B);
			//	printf("i=%lld j=%lld Sum=%lld\n",i,j,Sum);
				dp[i]=max(dp[i],dp[j-1]+Sum+(a[i]-a[j]<=B));
			}
			//printf("dp[%lld]=%lld\n",i,dp[i]);
		}
		printf("%lld\n",(dp[2*n]==-INF)?-1:dp[2*n]);
	}
	return 0;
}