#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
const int INF = 0x3f3f3f3f;

int n, dp[200005];
LL A, B, a[400005];

pair<int, int> que[200005];
int fr, rr;
void qpush(int v, int i) {
    while(fr < rr && que[rr - 1].first >= v) rr--;
    que[rr++] = make_pair(v, i);
}
void qpop(int i) {
    if(fr < rr && que[fr].second == i) fr++;
}
int qtop() {
    return fr == rr ? INF : que[fr].first;
}
void solve() {
    scanf("%d%lld%lld", &n, &A, &B);
    for(int i = 0; i < 2 * n; i++) scanf("%lld", &a[i]);
    sort(a, a + 2 * n);

    fr = rr = 0;
    dp[0] = 0;
    int l = 0;
    for(int i = 0; i < n; i++) {
        qpush(dp[i], i);
        
        dp[i + 1] = a[2 * i + 1] - a[2 * i] <= B ? dp[i] : INF;
        while(l <= i && a[2 * i + 1] - a[2 * l] > A) qpop(l++);
        dp[i + 1] = min(dp[i + 1], qtop() + 1);
    }
    printf("%d\n", dp[n] == INF ? -1 : n - dp[n]);
}

int main() {
    int T;
    scanf("%d", &T);
    while(T--) solve();
    return 0;
}