#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N = 2e5 + 10, INF = 1e18, MOD = 1e9 + 7;
typedef pair<int, int> PII;
typedef unsigned long long ull;
int dx[] = {0, 0, 1, -1}, dy[] = {1, -1, 0, 0};
int arr[N], brr[N];
bool st[N];
int n, m, k, w;

void solve()
{
	cin >> n >> m >> k >>  w;
	vector<int> red(n), black(m + 2);
	map<PII,vector<int>> mp;
	
	for(int i = 0; i < n; i ++) cin >> red[i];
	for(int i = 1; i <= m; i ++) cin >> black[i];
	black[0] = 0, black[m + 1] = w + 1;
	
	sort(black.begin(), black.end());
	sort(red.begin(),red.end());
	for(int i = 0; i < n; i ++){
		int b = red[i];
		
		int l = 0, r = m + 1;
		while(l < r){
			int mid = (l + r + 1) >> 1;
			if(black[mid] < b) l = mid;
			else r = mid - 1;
		}
		int ml = black[l];
		
		l = 0, r = m + 1;
		while(l < r){
			int mid = (l + r) >> 1;
			if(black[mid] > b) r = mid;
			else l = mid + 1;
		}
		int mr = black[l];
		
		mp[{ml,mr}].push_back(b);
	}
	
	vector<int> ans;
	for(auto [x,y] : mp){
		auto [bl, br] = x;
		int l = bl;
		int cnt = 0;
		vector<PII> vi;
		for(auto c : y){
			if(c > l){
				int d = c - l - 1;
				cnt += d;
				vi.push_back({c, d});
				l = c + k - 1;
			}else continue;
		}
		int len = vi.size();
		if(vi[len - 1].first + k - 1 >= br && cnt < vi[len - 1].first + k - br){
			cout << -1 << "\n";
			return;
		}
		int temp = vi[len - 1].first + k - br;
		for(int i = len - 1; i >= 0; i --){
			ans.push_back(vi[i].first - temp);
			temp -=vi[i].second;
		}
	}
	cout << ans.size() << "\n";
	for(auto x : ans) cout << x << " ";
	cout << "\n";
}

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