#include <iostream>
#include <cstdio>
#include <cstring>
#include <vector>
#include <functional>
#include <cassert>

bool solve(int L, const std::vector<int> &a, int R, int w, std::function<void(int)> callback) {
    int n = a.size();
    std::vector<int> p(n), pre(n);
    // std::cerr << "debug: ";
    // for(int i = 0; i < n; ++i) std::cerr << a[i] << char(i == n - 1 ? 10 : 32);
    int l = -1;
    for(int r = 0; r < n; ++r) {
        while(a[l + 1] <= a[r] - w) l++;
        if(l < 0) p[r] = std::max(L + 1, r - w + 1);
        else      p[r] = std::max(p[l] + w, r - w + 1);
        pre[r] = l;
    }
    if(p[n - 1] + w - 1 >= R) return false;
    for(int i = n - 1; i >= 0; i = pre[i]) callback(p[i]);
    return true;
}

void work() {
    int n, m, k, w;
    std::cin >> n >> m >> k >> w;
    std::vector<std::pair<int, int>> c(n + m + 2);
    for(int i = 0; i < n; ++i) std::cin >> c[i].first, c[i].second = 1;
    for(int i = n; i < n + m; ++i) std::cin >> c[i].first, c[i].second = 0;
    c[n + m] = {w + 1, 0};
    c[n + m + 1] = {0, 0};
    std::sort(c.begin(), c.end());

    int ans = 0, l = 0;
    std::vector<int> strip;
    while(l < c.size()) {
        int pre_l = l; l++;
        while(l < c.size() && c[l].second) l++;
        if(l == c.size()) break;
        assert(!c[pre_l].second && !c[l].second);
        if(pre_l == l - 1) continue;
        if(c[l].first - c[pre_l].first - 1 < k) {
            std::cout << "-1\n";
            return ;
        }
        std::vector<int> a(l - pre_l - 1);
        for(int i = pre_l + 1; i < l; ++i) a[i - pre_l - 1] = c[i].first;
        bool flag = solve(c[pre_l].first, a, c[l].first, k, [&](int pos) {
            ans++;
            strip.push_back(std::min(pos, c[l].first - k));
        });
        if(!flag) return std::cout << "-1\n", void(0);
        // pre = c[l].first;
    }
    std::cout << ans << char(10);
    for(int i = 0; i < strip.size(); ++i) std::cout << strip[i] << char(i == strip.size() - 1 ? 10 : 32);
    return ;
}

int main() {
    std::ios::sync_with_stdio(false);
    int T; std::cin >> T; while(T--) work();
    return 0;
}