#pragma GCC optimize(2)
#pragma GCC optimize("Ofast")
#include<map>
#include<set>
#include<cmath>
#include<ctime>
#include<queue>
#include<stack>
#include<cstdio>
#include<vector>
#include<string>
#include<bitset>
#include<numeric>
#include<cstring>
#include<cstdlib>
#include<iostream>
#include<algorithm>
using namespace std;
const int MAXN=2e5+10;
const int N=2e5;
const int INF=0x3f3f3f3f;
const long long LINF=0x3f3f3f3f3f3f3f3f;
int n,m,k,L,cnt=0;
int a[MAXN],b[MAXN];
basic_string <int> s[MAXN],res[MAXN];
basic_string <int> ans;
inline bool work(int id){
	res[id].clear();
	if(s[id].empty()){
		return true;
	}
	int len=b[id+1]-b[id];
	if(len<=k){
		return false;
	}
	int lst=-k;
	// printf("work %d\n",len);
	// for(int x:s[id])
	// {
	// 	printf("%d ",x);
	// }puts("");
	basic_string <int> cur;
	for(int x:s[id])
	{
		if(x>=lst+k){
			// printf("!%d\n",x);
			lst=x;
			cur.push_back(x);
		}
	}
	if(lst>len-k){
		int ext=lst-(len-k),siz=cur.size();
		for(int i=siz-1;i;i--)
		{
			int now=cur[i]-k-cur[i-1];
			if(now>=ext){
				cur[i]-=ext;
				ext=0;
				break;
			}
			else{
				ext-=now;
				cur[i]-=now;
			}
		}
		if(ext){
			return false;
		}
	}
	for(int x:cur)
	{
		res[id].push_back(x+b[id]);
	}
	return true;
}
inline void solve(){
	scanf("%d%d%d%d",&n,&m,&k,&L);
	for(int i=1;i<=n;i++)
	{
		scanf("%d",&a[i]);
	}
	sort(a+1,a+1+n);
	s[0].clear();
	for(int i=1;i<=m;i++)
	{
		scanf("%d",&b[i]);
		s[i].clear();
	}
	sort(b+1,b+1+m);
	m++;
	b[m]=L+1;
	for(int i=1;i<=n;i++)
	{
		int pos=lower_bound(b+1,b+1+m,a[i])-b-1;
		s[pos].push_back(a[i]-b[pos]);
	}
	ans.clear();
	for(int i=0;i<=m;i++)
	{
		if(!work(i)){
			puts("-1");
			return ;
		}
		ans+=res[i];
	}
	printf("%d\n",(int)ans.size());
	for(int x:ans)
	{
		printf("%d ",x);
	}
	putchar('\n');
}
signed main(){
	#ifdef LOCAL
	freopen("data.in","r",stdin);
	freopen("data.out","w",stdout);
	atexit([](){fprintf(stderr,"%.3lfs\n",(double)clock()/CLOCKS_PER_SEC);});
	#endif
	int t;
	scanf("%d",&t);
	while(t--)
	{
		solve();
	}
	return 0;
}