#include <bits/stdc++.h>

#define endl "\n"
using namespace std;

typedef pair<int,int> PII;
const int N = 2e5 + 5;
int n, m, k, w;

struct node{
    int x, c;
};

void solve(){

    cin >> n >> m >> k >> w;
    vector<node> a;

    for(int i = 1; i <= n; i++){
        int x;
        cin >> x;
        a.emplace_back(x, 1);
    }
    for(int i = 1; i <= m; i++){
        int x;
        cin >> x;
        a.emplace_back(x, 0);
    }
    a.emplace_back(w + 1, 0);
    sort(a.begin(), a.end(), [&](node x, node y){
        return x.x < y.x;
    });

    vector<int> p;
    int last = 0, prel = 0, prer = 0, ans = 0;
    for(auto [x, c] : a){
        if(c == 0){
            if(prel >= x){
                cout << -1 << endl;
                return;
            }
            last = x;
            prer = min(prer, x - 1);
        }
        else{
            if(prer >= x){
                prel = max(prel, x);
                continue;
            }
            if(prel != 0) p.push_back(prel - k + 1);
            // cout << x << " " << c << " " << prel << " " << prer << endl;
            ans ++;
            prel = max({last + k, x, prel + k});
            prer = x + k - 1;
            // cout << x << " " << c << " " << prel << " " << prer << endl;
        }
    }
    p.push_back(prel - k + 1);
    
    cout << ans << endl;
    for(int x : p){
        cout << x << " ";
    }
    cout << endl;
}

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int _ = 1;
    cin >> _;
    while(_--){
        solve();
    }
}