#include<bits/stdc++.h>
using namespace std;
const int N=2e5+10;
int a[N],b[N];
struct shu{
	int zhi,bh;
}q[N];
int flag=1;
bool cmp(shu a,shu b){
	if(a.zhi==b.zhi && a.bh!=b.bh){
		flag=0;
	}
	return a.zhi<b.zhi;
}
signed main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int n,m,k,w;
	int t;
	cin >> t;
	while(t--){
		flag=1;
		vector<int> da;
		cin >> n >> m >> k >> w;
		for(int i=1;i<=n;i++){
			cin >> q[i].zhi;
			q[i].bh=1;
		}
		for(int i=n+1;i<=n+m;i++){
			cin >> q[i].zhi;
			q[i].bh=2;
		}
		q[n+m+1].bh=2;
		q[n+m+1].zhi=w+1;
		sort(q+1,q+1+n+m+1,cmp);
		if(flag){
			int bws=0,aws=0,awm=0,bwm=0,fk=1;
			int flag1=1;
			for(int i=1;i<=n+m+1;i++){
				if(q[i].bh==2){
					bws=bwm;
					bwm=i;
					if(!(aws==0&&awm==0) && fk==0){
						int bl=q[bwm].zhi-q[bws].zhi-1;
						int al=q[awm].zhi-q[aws].zhi+1;
						int bian=(al+k-1)/k*k;
						if(bian>bl){
							flag1=0;
							break;
						}
						int tou=min(q[bwm].zhi-bian,q[aws].zhi);
						for(int i=0;i<(al+k-1)/k;i++){
							da.push_back(tou+k*i);
						}
					}
					fk=1;
				}
				if(q[i].bh==1){
					if(fk==1){
						fk=0;
						aws=i;
						awm=i;
					}
					else{
						awm++;
					}
				}
			}
			if(flag1){
				int len2=da.size();
				cout << len2 << "\n";
				for(int i=0;i<len2;i++){
					cout << da[i] << " ";
				}
				cout << "\n";
			}
			else cout << "-1" << "\n";
		}
		else{
			cout << "-1" << "\n";
		}
	}
	return 0;
}