#include<bits/stdc++.h>

#define int long long
#define fast ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
using namespace std;

void solve();

signed main() {
    fast
    int t = 1;
    cin >> t;
    while (t--) solve();
}

const int N = 2e5 + 10;

using pii = pair<int, int>;

#define red 1
#define black 0

int n, m, k, w;
int a[N], b[N];
vector<pii> cells;


void solve() {
    cin >> n >> m >> k >> w;
    cells.clear();
    for(int i = 1; i <= n; i++) cin >> a[i], cells.emplace_back(a[i], red);
    for(int i = 1; i <= m; i++) cin >> b[i], cells.emplace_back(b[i], black);
    cells.emplace_back(0, black);
    cells.emplace_back(w + 1, black);
    sort(cells.begin(), cells.end());

    vector<int> res;

    for(int i = 1; i < cells.size() - 1; i++){
        if(cells[i].second == black) continue;
        int lb = cells[i - 1].first;
        int j = i;
        while(cells[j + 1].second == red) j++;
        int rb = cells[j + 1].first;

        vector<int> strips;
        int last_cover_pos = -1;
        for(int t = i; t <= j; t++){
            if(last_cover_pos < cells[t].first){
                strips.emplace_back(cells[t].first);
                last_cover_pos = cells[t].first + k - 1;
            }
        }
        if(strips.size() > (rb - lb - 1) / k){
            cout << -1 << '\n';
            return;
        }
        if(last_cover_pos < rb){
            res.insert(res.end(), strips.begin(), strips.end());
            continue;
        }
        for(int t = 0; t < strips.size(); t++){
            if(strips[t] + (strips.size() - t) * k - 1 < rb) continue;
            int pos = rb - (int)(strips.size() - t) * k;
            while(t < strips.size()) strips[t] = pos, t++, pos += k;
        }
        res.insert(res.end(), strips.begin(), strips.end());
        i = j;
    }
    cout << res.size() << '\n';
    for(int ls : res){
        cout << ls << ' ';
    }
    cout << '\n';
}