#include<bits/stdc++.h>
using namespace std;
#define mk make_pair
const int N=5e6+5;
int T,n,m,w,K;
int ans[N],anss,a[N],b[N];
signed main(){
	ios::sync_with_stdio(0);
	cin>>T;
	while(T--){
		cin>>n>>m>>K>>w;
		for(int i=1;i<=n;++i)cin>>a[i];
		for(int j=1;j<=m;++j)cin>>b[j];
		sort(a+1,a+n+1);
		sort(b+1,b+m+1);
		anss=0;
		b[m+1]=w+1;
		int j=1,op=0;
		for(int i=1;i<=m+1;++i){
			int ls=j;
			while(a[j]<b[i]&&j<=n)++j;
			int rs=j-1,mx=a[ls]-1;
			if(rs<ls)continue;
			int fl=anss;
			for(int k=ls;k<=rs;++k)
			if(mx<a[k])ans[++anss]=a[k],mx=a[k]+K-1;
			if(mx>=b[i]){
//			cout<<mx<<"CNMCNM\n";
				int mn=b[i]-K;
				ans[anss]=mn;
//				cout<<mn<<" "<<ans[1]<<' '<<fl<<"FSDJLK\n";
				for(int k=anss-1;k>fl;--k)
				if(ans[k]+K-1>=ans[k+1])ans[k]=ans[k+1]-K;
//				cout<<mn<<"CNMCNMCNM\n";
				if(ans[fl+1]<a[ls]){
					op=1;
					break;
				}
			}
		}
		if(op)cout<<-1<<'\n';
		else{
			cout<<anss<<'\n';
			for(int i=1;i<=anss;++i)
			cout<<ans[i]<<" ";
			cout<<'\n';
		}
	}
}