#include <bits/stdc++.h>

using std::cin, std::cout, std::ios;

void solve() {
	int n, m, k, w; cin >> n >> m >> k >> w;
	std::vector <int> a(n); for(auto &i : a) cin >> i;
	std::vector <int> b(m); for(auto &i : b) cin >> i;

	std::sort(a.begin(), a.end()); std::sort(b.begin(), b.end());
	b.emplace_back(w+1);

	std::vector <int> ans;

	int p = 0;

	for(auto i : a) {
		if(ans.size() and i < *std::prev(ans.end()) + k) continue;
		p = std::max(p, 0);
		while(p < m and b[p] < i) p ++;
		p --;
		// prev: b[p], nxt: b[p+1]
		if(~p and b[p+1] - b[p] - 1 < k) {
			cout << -1 << '\n';
			return;
		}
		int cur = std::min(i, b[p+1] - k);
		if(cur < 1 or (ans.size() and cur < *std::prev(ans.end()) + k)) {
			cout << -1 << '\n';
			return;
		}
		ans.emplace_back(cur);
	}
	cout << ans.size() << '\n';
	for(auto i : ans) cout << i << ' ';
	cout << '\n';
}

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