#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define mk make_pair
#define S second
#define F first

vector<int> ans;
int k;

int comp(vector<int> red, int lt, int rt) {
    if (rt == 0) return 0;
    int n = red.size();
    vector<int> dp(n + 1);
    dp[n] = rt;

    for (int i = n - 1; i >= 0; i--) {
        int l = red[i] - k + 1;
        int r = red[i] + 1;

        if (red[i] >= dp[i + 1]) {
            dp[i] = dp[i + 1];
            continue;
        }

        // Binary search to find the best mid value
        while (l + 1 < r) {
            int mid = (l + r) / 2;
            int next = lower_bound(red.begin() + i, red.end(), mid + k) - red.begin();
            if (next >= n || mid + k > dp[next]) r = mid; // Adjust condition for edge case
            else l = mid;
        }

        if (l <= lt) return -1;

        dp[i] = l;
    }

    int cur = dp[0];
    ans.push_back(cur);

    for (int i = 1; i < n; i++) {
        if (cur + k >= red[i]) continue;
        cur = dp[i];
        ans.push_back(cur);
    }

    return 0; // Added return statement to indicate success
}

void solve() {
    ans.clear();
    int n, m, w;
    cin >> n >> m >> k >> w;

    vector<int> a(n), b(m);
    vector<pair<int, bool>> v;

    v.emplace_back(0, 0);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
        v.emplace_back(a[i], 1);
    }
    for (int j = 0; j < m; j++) {
        cin >> b[j];
        v.emplace_back(b[j], 0);
    }
    v.emplace_back(w + 1, 0);

    sort(v.begin(), v.end());
    vector<int> red;
    int blackprev = 0;

    for (auto &[i, isred] : v) {
        if (!isred) {
            if (comp(red, blackprev, i) == -1) {
                cout << "-1\n";
                return;
            }
            blackprev = i;
            red.clear();
        } else {
            red.push_back(i);
        }
    }

    cout << ans.size() << '\n';
    for (auto i : ans) {
        cout << i << " ";
    }
    cout << '\n';
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    int t;
    cin >> t;
    while (t--) solve();
}