#include <bits/stdc++.h>

#define int long long
#define fadd(a,b,c) for (int a=b;a<=c;a++)
#define fsub(a,b,c) for (int a=b;a>=c;a--)
#define F first
#define S second
#define CYes cout << "Yes\n"
#define CNo cout << "No\n"
#define CYES cout << "YES\n"
#define CNO cout << "NO\n"
#define println(a) cout << (a) << '\n'

using namespace std;

typedef long long LL;
typedef pair<int,int> PII;
void fastIO(){ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);}
class bhscer {
public:
    template<typename FIRST, typename ...PACK> static void debug(FIRST first, PACK... params) { std::cout<< first <<' '; debug(params...);}
    template<typename T> static void debug(T end) { std::cout << end << std::endl; }
};
const int N = 5e5;
int a[N], b[N];

void solve() {
	int n, m, k, w;
	cin >> n >> m >> k >> w;
	// map<int,bool> red;
	vector<int> all;
	map<int,int> allMp;
	for (int i=1;i<=n;i++) {
		cin >> a[i];
		// red[a[i]] = true;
		all.push_back(a[i]);
	}
	m += 2;
	b[1] = 0;
	b[m] = w+1;
	for (int i=2;i<m;i++) {
		cin >> b[i];
	}
	for (int i=1;i<=m;i++) {
		// red[b[i]] = false;
		all.push_back(b[i]);
	}
	sort(b+1, b+1+m);

	sort(all.begin(), all.end());
	all.erase(unique(all.begin(), all.end()), all.end());

	for (int i=0;i<all.size();i++) {
		allMp[all[i]] = i;
	}

	vector<int> ans;
	bool ok = true;
	for (int i=0;i<all.size()-1;) {

		// this must be a black.
		// find next black.
		int nextBIdx = upper_bound(b+1, b+1+m, all[i]) - b;
		int nextAllIdx = allMp[b[nextBIdx]];

		int wallL = all[i];
		int wallR = all[nextAllIdx];
		// cout << " here has a range: " << wallL << ' ' << wallR << endl;

		int lastCoverTo = 0;
		bool success = true;
		vector<int> ans1;
		for (int j=i+1;j<nextAllIdx;j++) {
			if (lastCoverTo >= all[j]) {
				continue;
			}

			if (all[j] + k-1 < wallR) {
				lastCoverTo = all[j] + k - 1;
				ans1.push_back(all[j]);
				continue;
			}

			// failed to start a cover
			// the final part end

			// cout << "leftly cover failed" << endl;

			success = false;
			break;
		}

		bool successAgain = true;
		if (!success) {
			ans1.clear();
			int preCoverTo = wallR-1 - k + 1;
			if (preCoverTo > wallL) {

				ans1.push_back(preCoverTo);
				for (int j=nextAllIdx-1;j>i;j--) {
					if (preCoverTo <= all[j]) {
						continue;
					}
					if (all[j]-k+1 > wallL) {
						preCoverTo = all[j]- k + 1;
						ans1.push_back(preCoverTo);
						continue;
					}

					successAgain = false;
				}
			} else {
				successAgain = false;
			}
		}

		if (!successAgain) {
			ok = false;
			break;
		}
		for (auto j: ans1) {
			ans.push_back(j);
		}

		i = nextAllIdx;

	}

	if (!ok) {
		cout << -1 << '\n';
		return;
	}
	cout << ans.size() << '\n';
	for (auto i:ans) {
		cout << i << ' ';
	}
	cout << '\n';
}
signed main() {
	fastIO();
	int _ = 1; cin >> _;
	while (_--) {
		solve();
	}
	
	return 0;
}