#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'
#define rep(i,a,b) for(int i=a;i<=b;i++)
#define frep(i,a,b) for(int i=a;i>=b;i--)

constexpr int maxn = 2e5 + 5;
constexpr int mod = 998244353;
int n, m, k, w;

void solve()
{
	cin >> n >> m >> k >> w;
	vector<pair<int, bool> > a(1, {0, 1});
	rep(i, 1, n) {int x; cin >> x; a.push_back({x, 0});}
	rep(i, 1, m) {int x; cin >> x; a.push_back({x, 1});}
	sort(a.begin() + 1, a.end());
	a.push_back({w + 1, 1});
	vector<pair<int, bool> > b = a;
	vector<int> ans(0);
	bool flag = 0;
	int pos = 0;
	for (int i = 1; i <= n + m; i++)
	{
		if (a[i].second) continue;
		int j = i + 1;
		while (j <= w && !a[j].second && a[j].first <= a[i].first + k - 1) j++;
		if (a[j].first - 1 - max(pos, a[i - 1].first) < k) {flag = 1; break;}
		int tmp = max({a[j - 1].first - k + 1, a[i - 1].first + 1, pos + 1});
		ans.push_back(tmp);
		pos = tmp + k - 1;
		for (int t = i; t < j; t++) a[t].second = 1;
	}
	// flag = 0;
	if (flag)
	{
		flag = 0;
		pos = w + 1;
		a = b;
		ans.resize(0);
		for (int i = n + m; i > 0; i--)
		{
			if (a[i].second) continue;
			int j = i - 1;
			while (j > 0 && !a[j].second && a[j].first >= a[i].first - k + 1) j--;
			if (min(pos, a[i + 1].first) - 1 - a[j].first < k) {flag = 1; break;}
			int tmp = min({a[j + 1].first, a[i + 1].first - k, pos - k});
			ans.push_back(tmp);
			pos = tmp;
			for (int t = j + 1; t <= i; t++) a[t].second = 1;
		}
	}

	if (flag) {cout << -1 << endl; return;}
	cout << ans.size() << endl;
	for (auto x : ans) cout << x << " ";
	cout << endl;
}

signed main()
{
	cin.tie(0); cout.tie(0);
	ios::sync_with_stdio(0);
	int _ = 1;
	cin >> _;
	while (_--) solve();
	return 0;
}