#include<bits/stdc++.h>
#define fi first
#define se second
#define MULT_TEST 1
using namespace std;
typedef long double ldb;
typedef unsigned long long ull;
const int INF = 0x3f3f3f3f;
const int MOD = 998244353;
inline int read() {
    int w = 0, f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9') {
        if (ch == '-') f = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9') {
        w = (w << 1) + (w << 3) + ch - 48;
        ch = getchar();
    }
    return w * f;
}
inline void Solve() {
    int n, m, k, w;
    n = read(), m = read(), k = read(), w = read();
    vector<int> a(n + 1), b(m + 2);
    for (int i = 1; i <= n; i++) a[i] = read();
    sort(a.begin() + 1, a.end());
    b[0] = 0, b[m + 1] = w + 1;
    for (int i = 1; i <= m; i++) b[i] = read();
    sort(b.begin(), b.end());
    vector<int> A;
    for (int i = 1; i <= m + 1; i++) {
        if (b[i] - b[i - 1] == 1) continue;
        int pos = b[i - 1] + 1, sum = 0;
        while (pos < b[i]) {
            pos = *lower_bound(a.begin() + 1, a.end(), pos);
            sum++, pos += k;
        }
        if (b[i] - b[i - 1] - 1 < sum * k)
            return printf("-1\n"), void();
        pos = b[i - 1] + 1;
        while (pos <= b[i] - k) {
            pos = *lower_bound(a.begin() + 1, a.end(), pos);
            if (b[i] - pos <= sum * k) {
                int t = b[i] - k;
                for (int j = 1; j <= sum; j++, t -= k) A.push_back(t);
                break;
            }
            sum--, A.push_back(pos), pos += k;
        }
    }
    printf("%d\n", (int)A.size());
    for (auto u : A) printf("%d ", u);
    puts("");
}
signed main() {
    int _ = 1;
#if MULT_TEST
    _ = read();
#endif 
    while (_--) Solve();
    return 0;
}