#include <bits/stdc++.h>

using namespace std;

const int N = 4e5 + 5;

long long a[N], f[N];
long long mx[1 << 20];

void build(int k, int l, int r) {
    mx[k] = 1e18;
    if (l == r) {
        return;
    }
    int mid = (l + r) >> 1;
    build(k << 1, l, mid);
    build(k << 1 | 1, mid + 1, r);
}

void modify(int k, int l, int r, int x, long long y) {
    mx[k] = min(mx[k], y);
    if (l == r) return;
    int mid = (l + r) >> 1;
    if (x <= mid) modify(k << 1, l, mid, x, y);
    else modify(k << 1 | 1, mid + 1, r, x, y);
}

long long query(int k, int l, int r, int x, int y) {
    if (l > y || r < x) return 1e18;
    if (l >= x && r <= y) return mx[k];
    int mid = (l + r) >> 1;
    return min(query(k << 1, l, mid, x, y), query(k << 1 | 1, mid + 1, r, x, y));
}

signed main() {
    int T; scanf("%d", &T);
    while (T--) {
        int n; scanf("%d", &n);
        long long A, B; scanf("%lld%lld", &A, &B);
        for (int i = 1; i <= 2 * n; ++i) {
            scanf("%lld", &a[i]), f[i] = 1e18;
        }
        sort(a + 1, a + n + 1);
        a[0] = 0;
        for (int i = 2; i <= n + n; i += 2) {
            if (a[i] - a[i - 1] > A) {
                a[0] = 1;
            }
        }
        if (a[0]) {
            puts("-1");
            continue;
        }
        build(1, 0, n + n), modify(1, 0, n + n, 0, 0ll);
        for (int i = 2, j = 1, k = 1; i <= 2 * n; i += 2) {
            while (a[i] - a[j] > A) j += 2;
            while (k <= i && a[i] - a[k] > B) k += 2;
            f[i] = f[i - 2] + (a[i] - a[i - 1] > B);
            if (j + 1 != i) {
                if (a[i - 1] - a[i - 2] > B) {
                    j = k = i - 1;
                } else {
                    f[i] = min(f[i], query(1, 0, n + n, j - 1, n + n) + 1);
                    f[i] = min(f[i], query(1, 0, n + n, k - 1, n + n));
                }
            }
            modify(1, 0, n + n, i, f[i]);
        }
        printf("%lld\n", n - f[n + n]);
    }
    return 0;
}