#include<bits/stdc++.h>
#define int long long
#define double long double
using namespace std;
 
const int N=2e5+10;
const int M=0x3f3f3f3f3f3f3f3f;
int a[N],b[N];


signed main()
{
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	int T;cin>>T;
    while(T--)
    {
        int n,m,k,w;cin>>n>>m>>k>>w;
        for(int i=1;i<=n;i++) cin>>a[i];
        for(int i=1;i<=m;i++) cin>>b[i];
        sort(a+1,a+n+1);
        sort(b+1,b+m+1);
        b[m+1]=w+1;
        int ans=0,ok=1,l=0,r=0;
        queue<int> q;
        for(int i=1,j=1;i<=n;i++)
        {
            while(j<=m&&b[j]<a[i]) j++;
            if(r<a[i]&&a[i]+k-1<b[j]) q.push(a[i]),r=max(r,a[i]+k-1);
            else if(r<a[i]&&a[i]+k-1>=b[j])
            {
                if(b[j]-(r+1)>=k&&b[j]-1<=w)
                {
                    q.push(b[j]-k);
                }
                else ok=0;
                r=max(r,b[j]-1);
            }
        }

        if(ok) 
        {
            cout<<q.size()<<"\n";
            while(q.size())
            {
                cout<<q.front()<<" ";
                q.pop();
            }
            cout<<"\n";
        }
        else cout<<"-1\n";
    }
	
	return 0;
}