#include <bits/stdc++.h>

using namespace std;

using LL = long long;
#define endl '\n'
using db = double;
template <class T>
using max_heap = priority_queue<T>;
template <class T>
using min_heap = priority_queue<T, vector<T>, greater<T>>;

void solve()
{
    LL n, A, B;
    cin >> n >> A >> B;
    // cerr << "A = " << A << " B = " << B << endl;
    vector<LL> a(n * 2);
    for (int i = 0; i < n * 2; ++i)
        cin >> a[i];

    sort(a.begin(), a.end());

    multiset<LL> ms(a.begin(), a.end());

    int ok = 1, ans = 0;
    for (int i = 0; i < n; ++i)
    {
        auto it = ms.begin();
        LL x = *it;
        // cerr << "x + A = " << x + A << endl;
        // cerr << "x + B = " << x + B << endl;
        auto itA = prev(ms.upper_bound(x + A));
        auto itB = prev(ms.upper_bound(x + B));

        if (itB != it)
        {
            ans++;
            // cerr << *it << " " << *itB << endl;
            ms.erase(it);
            ms.erase(itB);
        }
        else if (itA != it)
        {
            // cerr << *it << " " << *itA << endl;
            ms.erase(it);
            ms.erase(itA);
        }
        else
        {
            ok = 0;
            break;
        }
    }
    if (ok)
        cout << ans << endl;
    else
        cout << -1 << endl;
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int T;
    cin >> T;
    while (T--)
        solve();
    return 0;
}