#include<bits/stdc++.h>
using namespace std;
#define int long long
#define ls(p) (p<<1)
#define rs(p) (p<<1|1)
#define mid ((l+r)>>1)
void solve()
{
	int n,m,k,w;
	cin>>n>>m>>k>>w;
	vector<int> a(n+1),b(m+2);
	for(int i=1;i<=n;++i)
	{
		cin>>a[i];
		// cout<<a[i]<<"??????????"<<endl;
	}
	for(int i=1;i<=m;++i)
	{
		cin>>b[i];
	}
	b[m+1]=w+1;
	sort(a.begin()+1,a.end());
	sort(b.begin()+1,b.end());

	vector<int> p;
	vector<int> nxt(n+1),pre(n+1);
	for(int i=1;i<=n;++i)
	{
		int pos=a[i];
		int t=upper_bound(b.begin()+1,b.end(),pos)-b.begin();
		nxt[i]=b[t];
		pre[i]=b[t-1];
	}
	int tot=p.size();
	auto check=[&](int l,int r) -> int
	{
		int t=lower_bound(b.begin()+1,b.end(),l)-b.begin();
		if(b[t]<=r) return 0;
		return 1;
	};
	for(int i=1;i<=n;++i)
	{
		int pos=a[i];
		if(tot>0&&p.back()+k-1>=pos) continue;
		int st=min(pos,nxt[i]-k);
		if(st<=pre[i])
		{
			cout<<-1<<'\n';
			return;
		}
		int lst=st;
		for(int i=tot-1;i>=0;--i)
		{
			if(p[i]+k-1>=lst)
			{
				int newpos=lst-k;
				if(check(newpos,newpos+k-1))
				{
					p[i]=newpos;
					lst=newpos;
				}
				else
				{
					cout<<-1<<'\n';
					return;
				}
			}
			else break;
		}
		++tot;
		p.emplace_back(st);
	}
	cout<<tot<<'\n';
	for(int i=0;i<tot;++i)
	{
		cout<<p[i]<<' ';
	}
	cout<<'\n';
}
signed main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	int T=1;
	cin>>T;
	while(T--) solve();
	return 0;
}