#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N=1e6+10,MOD=998244353;
int a[N],b[N],c[N];
signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr), cout.tie(nullptr);

    int t=1;
    cin>>t;
    while(t--){
        int n,m,k,w;
        cin>>n>>m>>k>>w;
        for(int i=0;i<n;i++)cin>>a[i];
        for(int i=0;i<m;i++)cin>>b[i];
        sort(a,a+n);
        sort(b,b+m);
        vector<int> v;
        int flag=1,pre=0;
        for(int i=0;i<n;i++){
            int u= lower_bound(b,b+m,a[i])-b;
            if(u==m){
                if(w-a[i]+1>=k) {
                    v.push_back(a[i]);
                    continue;
                }else{
                    if(w-k>pre){
                        v.push_back(w-k);
                        continue;
                    }
                }
            }
            if(b[u]-max(b[u-1],pre)<=k){
                flag=0;
                break;
            }else{
                int x;
                if(b[u]-a[i]>=k){
                    v.push_back(a[i]);
                    x= upper_bound(a,a+n,a[i]+k-1)-a;
                    pre=a[i]+k-1;
                }else{
                    v.push_back(b[u]-k);
                    x= upper_bound(a,a+n,b[u]-1)-a;
                    pre=b[u]-1;
                }
                i=x-1;
            }
        }
        if(flag){
            cout<<v.size()<<"\n";
            for(auto x:v){
                cout<<x<<" ";
            }
        }else{
            cout<<"-1";
        }
        cout<<"\n";
    }

}