#include<bits/stdc++.h>
#define int long long
#define endl '\n'
using namespace std;

int rec(vector<int> &reds, int range, int r, int K, vector<int> &pick){
	int ans = 0;
	int it = 0;
	int nxt = 0;
	vector<int> tmp;
	while(it < reds.size()){
		nxt = reds[it] + K;
		tmp.push_back(reds[it]);
		ans ++;
		it = lower_bound(reds.begin(), reds.end(), reds[it] + K) - reds.begin();
	}
	int got = 0;
	int last = r;
	reverse(tmp.begin(), tmp.end());
	for(int &i : tmp){
		got = last - i;
		last = i;
		i -= max(0ll, K - got);
	}
	reverse(tmp.begin(), tmp.end());
	for(int i : tmp){
		pick.push_back(i);
	}
	reds.clear();
	return (range >= K * ans ? ans : -1);
}

void solve(){
	int N, M, K, W;
	cin >> N >> M >> K >> W;
	vector<pair<int, int>> cells;
	for(int i = 0; i < N; i ++){
		int a;
		cin >> a;
		cells.push_back({a, 1});
	}
	for(int j = 0; j < M; j ++){
		int a;
		cin >> a;
		cells.push_back({a, 0});
	}
	cells.push_back({W + 1, 0});
	vector<int> reds;
	int l = 0;
	int ans = 0;
	sort(cells.begin(), cells.end());
	vector<int> pick;
	for(auto [i, j] : cells){
		if(j){
			reds.push_back(i);
		}
		else{
			int range = i - l - 1;
			int t = rec(reds, range, i, K, pick);
			if(t < 0){
				cout << -1 << endl;
				return;
			}
			ans += t;
		}
	}
	cout << ans << endl;
	for(int i : pick){
		cout << i << " ";
	}
	cout << endl;
}

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