#include<bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef unsigned long long ull;

#define N 400010
int n;
ll A, B;
ll a[N];
int s[N];
int dp[N];
int mx[2][21][N];

int qry(int t, int l, int r)
{
    int p = __lg(r - l + 1);
    return max(mx[t][p][r], mx[t][p][l + (1 << t) - 1]);
}
void sol() {
    cin >> n >> A >> B;
    for (int i = 1; i <= 2 * n; i ++) cin >> a[i];
    sort(a + 1, a + 2 * n + 1);
    for (int i = 1; i <= n; i ++)
    {
        if (a[i * 2] - a[i * 2 - 1] > A)
        {
            cout << "-1\n";
            return ;
        }
        if (i == 1) s[i] = 0;
        else
        {
            s[i] = s[i - 1];
            s[i] += (a[i * 2 - 1] - a[i * 2 - 2] <= B);
        }
    } 
    for (int i = 1; i <= n; i ++)
    {
        dp[i] = 0;
        int l = 1, r = i, pos = i + 1;
        while (l <= r)
        {
            int mid = (l + r) >> 1;
            if (a[i * 2] - a[mid * 2 - 1] <= B)pos = mid, r = mid - 1;
            else l = mid + 1; 
        }
        if (pos <= i) 
        {
            dp[i] = max(dp[i], qry(0, pos - 1, i - 1) + i);
        }
        l = 1, r = i, pos = i + 1;
        while (l <= r)
        {
            int mid = (l + r) >> 1;
            if (a[i * 2] - a[mid * 2 - 1] <= A)pos = mid, r = mid - 1;
            else l = mid + 1;
        }
        dp[i] = max(dp[i], qry(1, pos - 1, i - 1) + s[i]);
        mx[0][0][i] = dp[i] - i;
        mx[1][0][i] = dp[i] - s[i + 1];
        for (int j = 1; j <= 20; j ++)
        {
            if (i - (1 << j) + 1 <= 0)break;
            mx[0][j][i] = max(mx[0][j - 1][i], mx[0][j - 1][i - (1 << j - 1)]);
            mx[1][j][i] = max(mx[1][j - 1][i], mx[1][j - 1][i - (1 << j - 1)]);
        }
    }
    cout << dp[n] << '\n';
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int t; cin >> t;
    while (t --) sol();
    return 0;
}