#include<bits/stdc++.h>
using namespace std;
#define N 400020
typedef long long ll;
const int inf=0x3f3f3f3f;
int n,dp[N],s[N];
ll A,B,a[N];
struct BIT{
	int b[N];
	inline int lowbit(int x){return x&(-x);}
	void init(int n){
		for(int i=1;i<=n;++i)b[i]=inf;
	}
	void Add(int x,int d){
		while(x){
			b[x]=min(b[x],d);
			x-=lowbit(x);
		}
	}
	int Ask(int x){
		int ans=inf;
		while(x<=n){
			ans=min(ans,b[x]);
			x+=lowbit(x);
		}
		return ans;
	}
}Bi;
void Solve(){
	cin>>n>>A>>B;
	for(int i=1;i<=2*n;++i){
		cin>>a[i];
	}
	sort(a+1,a+2*n+1);
	s[0]=s[1]=0;
	for(int i=2;i<=n;++i){
		s[i]=s[i-1]+(a[2*i-1]-a[2*i-2]<=B);
	}
	for(int i=1;i<=n;++i)dp[i]=-n-1;
	Bi.init(n);
	Bi.Add(1,0);
	for(int i=1,j=1;i<=n;++i){
		ll tmp=a[2*i]-a[2*i-1];
		if(tmp>A){
			cout<<-1<<'\n';
			return;
		}
		if(tmp>B){
			dp[i]=dp[i-1];
		}
		else{
			dp[i]=dp[i-1]+1;
		}
		if(i>1&&a[2*i-1]-a[2*i-2]>A)j=i-1;
		while(i<j&&a[2*i]-a[2*j-1]>A)++j;
		dp[i]=max(dp[i],-Bi.Ask(j)+s[i]+(a[2*i]-a[2*j-1]<=B));
		if(i<n)Bi.Add(i+1,dp[i]+s[i]);
	}
	cout<<(dp[n]<0?-1:dp[n])<<'\n';
}
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	int T;
	cin>>T;
	while(T--){
		Solve();
	}
	return 0;
}