#include <bits/stdc++.h>
#define pb emplace_back
#define fst first
#define scd second
#define mkp make_pair
#define uint unsigned
#define mems(a, x) memset((a), (x), sizeof(a))

using namespace std;
typedef long long ll;
typedef double db;
typedef unsigned long long ull;
typedef long double ldb;
typedef pair<ll, ll> pii;

const int maxn = 1000100;

ll n, m, K, W;
pii a[maxn];

void solve() {
	scanf("%lld%lld%lld%lld", &n, &m, &K, &W);
	for (int i = 1; i <= n; ++i) {
		scanf("%lld", &a[i].fst);
		a[i].scd = 0;
	}
	for (int i = 1; i <= m; ++i) {
		scanf("%lld", &a[i + n].fst);
		a[i + n].scd = 1;
	}
	int tot = n + m;
	a[++tot] = mkp(0, 1);
	a[++tot] = mkp(W + 1, 1);
	sort(a + 1, a + tot + 1);
	int j = -1;
	vector<int> ans;
	for (int i = 1; i <= tot; ++i) {
		if (a[i].scd) {
			if (j == -1) {
				j = i;
				continue;
			}
			ll cnt = 0, r = 0;
			for (int k = j + 1; k < i; ++k) {
				if (r < a[k].fst) {
					r = a[k].fst + K - 1;
					ans.pb(a[k].fst);
					++cnt;
				}
			}
			if (cnt * K > a[i].fst - a[j].fst - 1) {
				puts("-1");
				return;
			}
			j = i;
		}
	}
	printf("%d\n", (int)ans.size());
	for (int i = 0; i < (int)ans.size(); ++i) {
		printf("%d%c", ans[i], " \n"[i == (int)ans.size() - 1]);
	}
}

int main() {
	int T = 1;
	scanf("%d", &T);
	while (T--) {
		solve();
	}
	return 0;
}