#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define endl '\n'
const ll maxn = 10;
const ll inf = 3e9;
ll color[maxn];

ll a[maxn];
ll b[maxn];

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll t;
    cin >> t;
    while (t--) {
        ll n, m, k, w;
        cin >> n >> m >> k >> w;
        vector<pair<ll, ll>> vp;
        for (ll i = 1; i <= n; i++) {
            cin >> a[i];
        }
        for (ll i = 1; i <= m; i++) {
            cin >> b[i];
        }
        b[0] = 0, b[m + 1] = w + 1;
        a[n + 1] = inf;
        sort(a + 1, a + 1 + n);
        sort(b + 1, b + 1 + m);
        for (ll i = 1; i <= m + 1; i++) {
            vp.push_back({ b[i - 1],b[i] });
        }
        ll loc = 1;
        bool ok = true;
        vector<ll> ans;
        for (auto it : vp) {
            vector<ll> now;
            while (it.first >= a[loc]) loc++;
            while (a[loc] < it.second) {
                if (now.empty() || a[loc] - now[now.size() - 1] >= k) {
                    now.push_back(a[loc]);
                }
                loc++;
            }
            ll left = it.second;
            for (ll i = now.size() - 1; i >= 0; i--) {
                if (now[i] + k - 1 >= left) {
                    now[i] = left - k;
                    left = now[i];
                }
            }
            if (left <= it.first) {
                ok = false;
                break;
            }
            else {
                for (auto it2 : now) {
                    ans.push_back(it2);
                }
            }
        }
        if (ok) {
            cout << ans.size() << endl;
            for (auto it : ans) {
                cout << it << ' ';
            }
            cout << endl;
        }
        else {
            cout << -1 << endl;
        }
    }
    return 0;
}