#include<iostream>
#include<set>
#include<queue>
#include<map>
#include<cmath>
#include<string>
#include<vector>
#include<cstring>
#include<algorithm>
#include<unordered_map>

#define pb push_back
#define fi first
#define se second
#define int long long
#define all(x) (x).begin(),(x).end()
#define _for(i, a) for(int i = 0; i < (a); ++i) 
#define _rep(i, a, b) for(int i = (a);i <= (b); ++i)
#define IOS ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define u1 (u<<1)
#define u2 (u<<1|1)
#define endl '\n'
using namespace std;
typedef pair<int,int> PII;

const int INF=0x3f3f3f3f;
const int P=1e9+7;
const int N=1e5+20,M=2*N;
int n,m,k,w,num;
void solve(){
	vector<int> v;
	cin>>n>>m>>k>>w;
	priority_queue<int,vector<int>,greater<>> q;
	_for(i,n){
		cin>>num;
		q.push(num);
	}
	_for(i,m){
		cin>>num;
		v.pb(num);
	}
	v.pb(0);
	v.pb(w+1);
	sort(all(v));
	vector<int> res;
	_rep(i,1,v.size()-1){
		vector<PII> ans;
		int l=v[i-1];
		int r=v[i];
		int now=l;
		while(q.size()&&q.top()<=r){
			int t=q.top();
			if(now<t){
				ans.pb({t,t-now-1});
//				cout<<t<<" "<<t-now-1<<" ";
				now=t+k-1;
//				cout<<now<<endl;
			}
			q.pop();	
		}
		int d=max(now-r+1,(int)0);
		for(int i=ans.size()-1;i>=0;i--){
			if(d==0){
				res.pb(ans[i].fi);
			}else{
				if(d>=ans[i].se){
					d-=ans[i].se;
				}else{
					int c=ans[i].fi-d;
					d=0;
					while(c<r){
						res.pb(c);
						c+=k;
					}
				}
			}
		}
		if(d>0){
			cout<<-1<<endl;
			return;
		}
	}
	cout<<res.size()<<endl;
	_for(i,res.size()){
		cout<<res[i]<<" ";
	}
	cout<<endl;
}
signed main(){
	IOS;
	int T=1;
	cin>>T;
	_rep(i,1,T){
		solve();
	}
	return 0;
}