#include <bits/stdc++.h>

using namespace std;
using i64 = long long;
void solve()
{
    i64 n, m, k, w;
    cin >> n >> m >> k >> w;

    vector<pair<i64, i64>> a(n + m + 2, {0, 0});
    for (int i = 1; i <= n; ++i)
    {
        cin >> a[i].first;
        a[i].second = 1;
    }
    for (int i = 1; i <= m; ++i)
    {
        cin >> a[i + n].first;
    }
    a[n + m + 1] = {1e18, 0};
    sort(a.begin(), a.end());

    i64 posl = 1, posr = 0, l = 0, r = 0;
    vector<i64> dp(n + m + 1, 0), pre(n + m + 1, -1);
    vector<i64> ans;

    vector<bool> alive(n + m + 1, 1);
    bool ok = 1;
    for (int i = 1; i <= n + m + 1; ++i)
    {
        if (a[i].second)
        {
            continue;
        }
        alive[i] = 0;
        r = a[i].first;
        posr = i - 1;
        dp[posl - 1] = a[posl - 1].first;
        i64 L = posl - 1, R = posl - 1;
        for (int j = posl; j <= posr; ++j)
        {
            i64 t = a[j].first - k + 1;
            while (L < R and (a[L + 1].first < t or !alive[L + 1]))
            {
                L++;
            }
            dp[j] = max(dp[L] + k, a[j].first);
            pre[j] = L;

            alive[j] = dp[j - 1] < a[j].first;
            R++;
        }
        if (dp[posr] >= r)
        {
            cout << -1 << '\n';
            return;
        }
        int cur = posr;
        while (~pre[cur])
        {
            ans.push_back(cur);
            cur = pre[cur];
        }
        posl = i + 1;
    }
    cout << ans.size() << '\n';
    for (auto id : ans)
    {
        cout << dp[id] - k + 1 << ' ';
    }
    cout << '\n';
}
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int t;
    cin >> t;
    while (t--)
    {
        solve();
    }
}