#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> Pr;
#define fi first
#define se second
#define mkp make_pair
#define pb emplace_back
// #define mid ((l+r)>>1)
#define popcnt __builtin_popcountll
const ll mod = 998244353;
inline ll read(){
	ll x=0, f=1; char ch=getchar();
	while(ch<'0' || ch>'9') { if(ch=='-') f=-1; ch=getchar(); }
	while(ch>='0' && ch<='9') x=x*10+ch-'0', ch=getchar();
	return x*f;
}
inline ll lg2(ll x){ return 63^__builtin_clzll(x); }
inline ll qpow(ll a,ll b){
	ll ans=1, base=a;
	while(b){
		if(b&1) ans=ans*base%mod;
		base=base*base%mod; b>>=1;
	}
	return ans;
}
void init(){ }

ll n,A,B,a[400005],dp[400005],qz[400005];

struct Queue{
	ll que[400005], hd, tp;
	void init(){ hd = 1, tp = 0; }
	void insert(ll x){
		while(hd<=tp && dp[que[tp]]-qz[que[tp]]<=dp[x]-qz[x]) tp--;
		que[++tp]=x;
	}
	void pop(ll x){
		while(hd<=tp && que[hd]<x) hd++;
	}
	ll get(){
		if(hd>tp) return -1;
		else return que[hd];
	}
}q[2];
ll pt;
void procedure(){
	pt=0;
	n=read(), A=read(), B=read(); q[0].init(); q[1].init();
	for(ll i=1;i<=2*n;i++) a[i]=read();
	sort(a+1, a+2*n+1);
	for(ll i=0;i<=2*n+1;i++) qz[i]=0;
	for(ll i=3;i<=2*n+1;i++){
		qz[i]=qz[i-2];
		if(a[i-1]-a[i-2]<=B) qz[i]++;
	}
	memset(dp, 0xc0, sizeof(dp));
	dp[0] = 0; q[0].insert(0);
	for(ll i=1;i<=2*n;i++){
		while(a[i]-a[pt+1]>A) pt++; q[i&1].pop(pt);
		ll p=q[i&1].get();
		if(~p) dp[i] = dp[p] + qz[i] - qz[p];
		if(i>1 && a[i]-a[i-1]<=B) dp[i] = max(dp[i], dp[i-2] + 1);
		q[i&1].insert(i);
	}

	if(dp[2*n]<0) puts("-1");
	else printf("%lld\n", dp[2*n]);
}
int main(){
	#ifdef LOCAL
		assert(freopen("input.txt","r",stdin));
		assert(freopen("output.txt","w",stdout));
	#endif
	ll T=read();
	init();
	while(T--) procedure();
	return 0;
}