#include <bits/stdc++.h>

using namespace std;

vector<int> solve(vector<int> a, int n, int k) {
  if (a.empty()) return {};
  map<int, int> from;
  int x = 1, l = max(a[0], k - 1), r = a[0] + k, ll = l + k, rr = l + k;
  for (int i = 1; i < a.size(); ++i) {
    if (a[i] < l) continue;
    from[a[i] + k] = l;
    if (a[i] < r) {
      l = a[i];
      rr = a[i] + k;
    } else if (a[i] < ll) {
      l = ll;
      r = a[i] + k;
      ll = rr = l + k;
    } else {
      l = a[i];
      ll = rr = r = a[i] + k;
    }
  }
  if (n <= l) return {-1};
  vector<int> res;
  int last = l;
  while (1) {
    res.push_back(last - k + 1);
    if (last == max(a[0], k - 1)) break;
    last = from.upper_bound(last)->second;
  }
  reverse(res.begin(), res.end());
  return res;
}

int main() {
  cin.tie(0)->sync_with_stdio(0);
  for (int tc = (cin >> tc, tc); tc--; ) {
    int n, m, k, w; cin >> n >> m >> k >> w;
    vector<int> a(n), b(m);
    for (auto& a: a) cin >> a;
    for (auto& b: b) cin >> b;
    sort(a.begin(), a.end());
    b.push_back(0);
    b.push_back(w + 1);
    sort(b.begin(), b.end());
    vector<int> ans;
    bool fail = 0;
    for (int i = 1, j = 0; i < m + 2; ++i) {
      vector<int> ta;
      while (j < n && a[j] < b[i]) ta.push_back(a[j++] - b[i - 1] - 1);
      auto cans = solve(move(ta), b[i] - b[i - 1] - 1, k);
      for (auto cans: cans) fail |= !~cans, ans.push_back(cans + b[i - 1] + 1);
    }
    if (fail) { cout << "-1\n"; continue; }
    cout << ans.size() << '\n';
    for (auto ans: ans) cout << ans << ' '; cout << '\n';
  }
}