#include <bits/stdc++.h>

using namespace std;

#define SZ(x) ((int)((x).size()))
#define lb(x) ((x) & (-(x)))
#define bp(x) __builtin_popcount(x)
#define bpll(x) __builtin_popcountll(x)
#define mkp make_pair
#define pb push_back
#define fi first
#define se second
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, int> pli;
typedef pair<ll, ll> pll;
typedef pair<double, int> pdi;

void solve() {
    int n; ll A, B;
    cin >> n >> A >> B;
    vector a(2 * n + 1, 0ll);
    for (int i = 1; i <= 2 * n; i++) {
        cin >> a[i];
    }
    sort(a.begin() + 1, a.begin() + 2 * n + 1);

    for (int i = 1; i <= 2 * n; i += 2) {
        if (a[i + 1] - a[i] > A) {
            cout << -1 << '\n';
            return ;
        }
    }

    vector sum(2, vector(2 * n + 1, 0));
    for (int i = 2; i <= 2 * n; i++) {
        sum[i & 1][i] = sum[i & 1][i - 2] + (a[i] - a[i - 1] <= B ? 1 : 0);
    }

    vector f(2 * n + 1, vector(2, 0));
    // brute force DP
    // for (int i = 2; i <= 2 * n; i++) {
    //     f[i][0] = f[i - 2][0] + (sum[i & 1][i] - sum[i & 1][i - 2]);
    //     for (int j = 1; j < i - 1; j++) {
    //         if (!((i ^ j) & 1)) {
    //             continue;
    //         }
    //         if (a[i] - a[j] > A) {
    //             continue;
    //         }
    //         f[i][1] = max(f[i][1], max(f[j - 1][0], f[j - 1][1]) + sum[j & 1][i - 1] - sum[j & 1][j]);
    //     }
    // }
    
    auto calc = [&](int p) -> int {
        return max(f[p - 1][0], f[p - 1][1]) - sum[p & 1][p];
    };

    deque<int> q0, q1;
    q1.push_back(1);
    for (int i = 2; i <= 2 * n; i++) {
        f[i][0] = f[i - 2][0] + (sum[i & 1][i] - sum[i & 1][i - 2]);
        while (!q0.empty() && a[i] - a[q0.front()] > A) {
            q0.pop_front();
        }
        while (!q1.empty() && a[i] - a[q1.front()] > A) {
            q1.pop_front();
        }

        if ((i & 1) && q0.empty()) {
            //
        } else if (!(i & 1) && q1.empty()) {
            //
        } else {
            int j = (i & 1) ? q0.front() : q1.front();
            f[i][1] = calc(j) + sum[j & 1][i - 1];
        }

        if (i & 1) {
            while (!q1.empty() && calc(q1.back()) < calc(i)) {
                q1.pop_back();
            }
            q1.push_back(i);
        } else {
            while (!q0.empty() && calc(q0.back()) < calc(i)) {
                q0.pop_back();
            }
            q0.push_back(i);
        }
    }
    
    int ans = max(f[2 * n][0], f[2 * n][1]);
    cout << ans << '\n';
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    int T;
    cin >> T;
    while (T--) solve();
    return 0;
}