#include "bits/stdc++.h"
#define int long long
#define ull unsigned long long
#define PII pair<int, int>
#define TIII tuple<int, int, int>
#define LL __int128
#define eps 1e-6
using namespace std;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
constexpr int N = 2e6 + 10, M = 2e6 + 10, mod = 1e9 + 7, inf = 1e18;
int n, m;

void solve()
{
    int k, w;
    cin >> n >> m >> k >> w;
    // cout << n << " " << m << " " << k << " " << w << endl;   
    vector<int> a(n + 1), b(m + 2);
    for(int i = 1; i <= n; i ++) cin >> a[i];
    for(int i = 1; i <= m; i ++) cin >> b[i];
    b[m + 1] = w + 1;
    sort(a.begin() + 1, a.end());
    sort(b.begin() + 1, b.end());
    vector<int> ans;
    int solved = 0; //待处理
    for(int i = 0; i <= m; i ++)
    {
        if(solved == n) break;
        int l = solved + 1, r = l;
        if(b[i + 1] < a[solved]) continue;
        //b]i] 和 b[i + 1] 之间的红格子
        while(r + 1 <= n && a[r + 1] > b[i] && a[r + 1] < b[i + 1]) 
        {
            r ++;
        }
        // cout << l << " " << r << endl;
        vector<int> pos;
        for(int j = l; j <= r; j ++)
        {
            if(pos.empty() || a[j] > pos.back() + k - 1) pos.emplace_back(a[j]); 
        }
        pos.emplace_back(b[i + 1]);
        for(int j = pos.size() - 2; j >= 0; j--)
        {
            if(pos[j] + k - 1 >= pos[j + 1])
            {
                pos[j] = pos[j + 1] - k;
            }
        }
        if(pos[0] <= b[i]) return cout << -1 << endl, void();
        for(int j = 0; j < pos.size() - 1; j++)
        {
            ans.emplace_back(pos[j]);
        }
        solved = r;
    }
    cout << ans.size() << endl;
    for(int i = 0; i < ans.size(); i ++)
    {
        cout << ans[i] << " \n"[i == ans.size() - 1];
    }
}

signed main()
{
    std::ios::sync_with_stdio(false);
    cin.tie(nullptr), cout.tie(nullptr);
    cout << fixed << setprecision(2);

#ifndef ONLINE_JUDGE
    freopen("in.txt", "rt", stdin);
    freopen("out.txt", "wt", stdout);
#endif

    int Cases = 1;
    cin >> Cases;
    while (Cases--)
    {
        solve();
    }
    return 0;
}