#include "bits/stdc++.h"
using namespace std;

#define ll long long 
#define INF 0x3f3f3f3f
#define LNF 0x3f3f3f3f3f3f3f3fll
#define MOD 998244353
#define pii pair<int, int>

#define N 100010
#define K 20

int main() {
#ifdef TEST
    freopen("zz.in", "r+", stdin);
#endif
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int t; cin >> t;
    while (t --) {
        int n, m, k, w; cin >> n >> m >> k >> w;
        
        vector<pii> arr;
        arr.emplace_back(0, 0);
        arr.emplace_back(w+1, 0);
        for (int i = 0; i < n; ++ i) {
            int a; cin >> a; arr.emplace_back(a, 1);
        }
        for (int i = 0; i < m; ++ i) {
            int b; cin >> b; arr.emplace_back(b, 0);
        }

        sort(arr.begin(), arr.end());

        vector<int> res;
        bool ok = 1;

        for (int i = 0, j = 0; i < arr.size() - 1; ++ i) {
            if (arr[i].second || !arr[i+1].second) continue;
            while (j <= i || arr[j].second) ++ j;

            int sz = arr[j].first - arr[i].first - 1;
            
            vector<int> cur; 
            cur.emplace_back(arr[i+1].first);

            for (int l = i+2; l < j; ++ l) {
                if (arr[l].first < cur.back() + k) continue;
                cur.emplace_back(arr[l].first);
            }

            if (1ll * k * cur.size() > sz) {
                ok = 0;
                break;
            }

            int lb = arr[i].first;
            int rb = arr[j].first;
            int d = cur.back() + k > rb ? (cur.back() + k - rb) : 0;

            for (int l = cur.size() - 1; l >= 0 && d; -- l) {
                int dis = l ? (cur[l] - cur[l-1] + k) : 0;
                if (!l) assert(cur[l] - lb >= d);
                cur[l] -= d;
                d = max(0, d - dis);
            }

            for (auto x : cur) res.emplace_back(x);
            i = j - 1;
        }

        if (!ok) {
            cout << -1 << '\n';
            continue;
        }

        for (int i = 0; i < res.size() - 1; ++ i) {
            int a = res[i], b = res[i+1];
            assert(a + k <= b);
        }

        cout << res.size() << '\n';
        for (auto x : res) cout << x << ' ';
        cout << '\n';
    }
}