#include <bits/stdc++.h>
using namespace std;
int n, m, k, w;
vector<int> op;
int check(vector<pair<int, int>> now) {
    vector<int> res;
    int len = now.size();
    if (len == 2) return 0;
    res.push_back(now[1].first);
    for (int i = 2; i < len - 1; ++i) {
        if ((int)res.back() + k - 1 >= now[i].first) continue;
        res.push_back(now[i].first);
    }
    if ((int)res.back() + k <= now.back().first) {
        for (int v : res) {
            op.push_back(v);
        }
        return (int)res.size();
    }
    res.back() = (now.back().first - k);
    int ct = res.size();
    for (int i = ct - 2; i >= 0; --i) {
        if (res[i] + k - 1 >= res[i + 1]) {
            res[i] = res[i + 1] - k;
        }
    }
    if (res[0] <= now[0].first) return -1;
    for (int v : res) {
        op.push_back(v);
    }
    return (int)res.size();
}
void solve() {
    cin >> n >> m >> k >> w;
    vector<pair<int, int>> t;
    for (int i = 0; i < n; ++i) {
        int x;
        cin >> x;
        t.push_back({x, 1});
    }
    for (int i = 0; i < m; ++i) {
        int x;
        cin >> x;
        t.push_back({x, -1});
    }
    op.clear();
    t.push_back({0, -1});
    t.push_back({w + 1, -1});
    sort(t.begin(), t.end());
    int cnt = n + m + 2;
    int ans = 0;
    for (int l = 0, r; l < cnt; l = r) {
        r = l + 1;
        vector<pair<int, int>> now;
        now.push_back(t[l]);
        while (t[r].second == 1) now.push_back(t[r]), r++;
        now.push_back(t[r]);
        int tt = check(now);
        if (tt == -1) {
            cout << -1 << '\n';
            return;
        }
        ans += tt;
    }
    cout << ans << '\n';
    for (int i = 0; i < ans; ++i) {
        cout << op[i] << " \n"[i == ans - 1];
    }
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int t = 1;
    cin >> t;
    while (t--) {
        solve();
    }
}