#include <bits/stdc++.h>
#define inf (0x7f7f7f7f)
#define Min(a, b) ((a) < (b) ? (a) : (b))
#define Max(a, b) ((a) > (b) ? (a) : (b))
typedef long long ll;
using namespace std;
template <class T>
inline void read(T &x){
	int ch = 0, f = 0; x = 0;
	for(; !isdigit(ch); ch = getchar()) if(ch == '-') f = 1;
	for(; isdigit(ch); ch = getchar()) x = x * 10 + ch - 48;
	if(f) x = -x;
}
const int N = 500005;
int dp[N], s[N], q[N], n;
ll a[N], A, B;
inline void solve(){
	read(n), read(A), read(B);
	for(int i = 1; i <= 2 * n; i++) read(a[i]);
	sort(a + 1, a + 2 * n + 1);
	int h = 1, t = 0;
	for(int i = 1; i <= n - 1; i++)
		s[i] = s[i-1] + (a[2*i+1] - a[2*i] <= B);
	for(int i = 1; i <= n; i++){
		dp[i] = -inf;
		if(a[2*i] - a[2*i-1] <= A)
			dp[i] = dp[i-1] + (a[2*i] - a[2*i-1] <= B);
		while(h <= t && a[2*q[h]+1] < A - a[2*i]) h++;
		if(h <= t) dp[i] = max(dp[i], dp[q[h]] - s[q[h]] + s[i-1]);
		if(i == n) break;
		while(h <= t && dp[q[t]] - s[q[t]] <= dp[i] - s[i]) t--;
		q[t++] = i;
		
	}
	if(dp[n] < 0) puts("-1"); else printf("%d\n", dp[n]);
}
int main(){
	int T; read(T);
	while(T--) solve();
	return 0;
}