#include<bits/stdc++.h>
using namespace std;
#define int long long
#define endl "\n"
const int N = 2e6 + 10;
const int mod = 1e9 + 7;
int a[N], b[N];
queue<int>ans;
deque<int>q[N];
void solve() {
    int n, m, len, w;
    cin >> n >> m >> len >> w;
    for (int i = 1; i <= n; i++)cin >> a[i];
    sort(a + 1, a + 1 + n);
    for (int i = 1; i <= m; i++)cin >> b[i];
    sort(b + 1, b + 1 + m);
    while (!ans.empty())ans.pop();
    b[0] = 0;
    b[m + 1] = w + 1;
    int posa = 1;
    for (int i = 0; i <= m; i++) {
        while (!q[i].empty())q[i].pop_back();
        int l, r;
        l = b[i];
        r = b[i + 1]; 
        while (posa <= n && l < a[posa] && a[posa] < r) {
            q[i].push_back(a[posa]);
            posa++;
        }
    }
    for (int i = 0; i <= m; i++) {
        int l, r;
        l = b[i];
        r = b[i + 1]; 
        deque<int>list;
        int poslen=l;
        while (!q[i].empty()) {
            int it=q[i].front();
            q[i].pop_front();
            if(it<=poslen)continue;
            else {
                poslen=it+len-1;
                list.push_back(it);
            }
        }
        if(poslen>=r&&list.size()*len>r-l+1-2){
                cout<<-1<<endl;
                return;
        }
        else {
            if(list.empty())continue;
            if(poslen>=r)poslen=r-len;
            else poslen=list.back();
            ans.push(poslen);
            list.pop_back();
            while(!list.empty()){
                int pos=list.back();
                list.pop_back();
                if(pos+len-1>=poslen){
                    pos=poslen-len;
                    poslen=pos;
                }
                ans.push(pos);
            }
        }
    }
    cout<<ans.size()<<endl;
    while(!ans.empty()){
        cout<<ans.front()<<" ";
        ans.pop();
    }
    cout<<endl;
}
signed main() {
    int _ = 1;
    cin >> _;//cout << "okk" << endl;
    while (_--) {
        solve();
    }
}
/*
4
5 2 3 16
7 11 2 9 14
13 5
3 2 4 11
6 10 2
1 11
2 1 2 6
1 5
3
2 1 2 6
1 5
2


*/