#include<bits/stdc++.h>
using namespace std;
constexpr int N=200005;
int n,m,k,w;
int a[N],b[N];
int f[N],g[N],lst[N];
pair<int,vector<int>> calc(int L,int R)
{
    int l=lower_bound(a+1,a+n+1,L)-a,r=upper_bound(a+1,a+n+1,R)-a-1;
    if(l>r) return make_pair(0,vector<int>());
    int res=0;
    f[l-1]=0,g[l-1]=L,lst[l-1]=l-1;
    for(int i=l;i<=r;i++)
    {
        if(g[i-1]>=a[i])
        {
            f[i]=f[i-1],g[i]=g[i-1],lst[i]=lst[i-1];
        }
        else
        {
            int pre=lower_bound(a+l,a+r+1,a[i]-k+1)-a-1;
            int to=upper_bound(a+l,a+r+1,g[pre])-a-1;
            // cerr<<"lst"<<pre<<" "<<g[pre]<<"\n";
            f[i]=f[to]+1,g[i]=g[pre]+1+k-1;
            lst[i]=to;
        }
        // cerr<<"find"<<i<<" "<<a[i]<<" "<<f[i]<<" "<<g[i]<<"\n";
    }
    if(g[r]>=R) return make_pair(-1,vector<int>());
    vector<int>pos;
    for(int u=r;u>=l;u=lst[u])
        pos.emplace_back(g[u]-k+1);//cerr<<"to"<<u<<"\n";
    reverse(pos.begin(),pos.end());
    // cerr<<"calc"<<L<<" "<<R<<" "<<f[r]<<" "<<g[r]<<'\n';
    return make_pair(f[r],pos);
}
void solve()
{
    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[0]=0;
    b[m+1]=w+1;
    int ans=0;
    vector<int>res;
    for(int i=0;i<=m;i++)
    {
        auto [cnt,pos]=calc(b[i],b[i+1]);
        if(cnt==-1)
        {
            cout<<-1<<"\n";
            return;
        }
        ans+=cnt;
        res.insert(res.end(),pos.begin(),pos.end());
    }
    cout<<ans<<"\n";
    for(int u:res)
        cout<<u<<" ";
    cout<<"\n";
    return;
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr),cout.tie(nullptr);
    int T;
    cin>>T;
    while(T--)
        solve();
    return 0;
}