#include<bits/stdc++.h>
#define up(a,b,c)for(int a=b;a<=c;++a)
#define dn(a,b,c)for(int a=b;a>=c;--a)
const int N=11e4;
using namespace std;
int T,n,m,k,w,a[N],b[N],cc;
bool ok;
vector<int>ccf;
int main()
{
    cin>>T;
    while(T--)
    {
        cin>>n>>m>>k>>w;
        up(i,1,n)cin>>a[i];
        up(i,1,m)cin>>b[i];
        b[0]=0,b[m+1]=w+1,cc=0,ccf.clear();
        sort(a+1,a+n+1),sort(b+1,b+m+1);
        int l=1,r=0;ok=1;
        up(i,0,m)
        {
            while(r<n&&a[r+1]<b[i+1])++r;
            if(l>r)continue;
            int L=b[i]-k+1,g=0;
            up(j,l,r)
                if(a[j]>=L+k)
                {
                    if(j>l)g=min(L+k-1-a[j-1],g);
                    if(j>l)ccf.push_back(L-g);
                    g+=a[j]-(L+k),++cc;
                    L=a[j];
                }
            g=min(L+k-1-a[r],g),ccf.push_back(L-g);//cout<<L<<' '<<g<<'\n';
            if(L+k-1-g>=b[i+1])
            {
                ok=0;break;
            }
            l=r+1;
        }
        if(!ok)cout<<"-1\n";
        else 
        {
            cout<<cc<<'\n';
            for(int v:ccf)cout<<v<<' ';
            cout<<'\n';
        }
    }
    return 0;
}