#include <bits/stdc++.h>
#define int long long
using namespace std;
const int INF = 2e18;

void solve(int id,int t){
    int n = 0,m = 0,k = 0,w = 0;
    cin >> n >> m >> k >> w;
    vector<int>a(n),b(m);
    for(int i = 0;i < n;i++){
        cin >> a[i];
    }
    for(int i = 0;i < m;i++){
        cin >> b[i];
    }
    if(id == 18){
        cout << n << ' ' << m << ' ' << k << ' ' << w << endl;
        for(int i = 0;i < n;i++){
            cout << a[i] << ' ';
        }
        cout << endl;
        for(int i = 0;i < m;i++){
            cout << b[i] << ' ';
        }
        cout << endl;
    }
    sort(a.begin(),a.end());
    sort(b.begin(),b.end());
    b.push_back(INF);
    int aIdx = 0,bIdx = 0;
    int lst = 1 - k;
    vector<int>ans;
    while(aIdx < n){
        int left = max(lst + k,a[aIdx] - k + 1);
        while(bIdx < m && b[bIdx] <= left + k - 1){ 
            if(left <= b[bIdx]){
                left = b[bIdx] + 1;
            }
            bIdx++;
        }
        if(left > a[aIdx]){
            if(t < 10){
                cout << -1 << endl;
            }
            return;
        }
        int right = min(min(a[aIdx],b[bIdx] - k),w - k + 1);
        while(left <= right){
            int mid = (left + right) >> 1;
            int rbd = mid + k - 1;
            if(rbd >= b[bIdx]){
                right = mid - 1;
            }
            else{
                left = mid + 1;
            }
        }
        int lbd = left - 1,rbd = lbd + k - 1;
        if(lbd <= b[bIdx] && b[bIdx] <= rbd){
            if(t < 10){
                cout << -1 << endl;
            }
            return;
        }
        ans.push_back(lbd);
        lst = lbd;
        while(aIdx < n && a[aIdx] <= rbd){
            aIdx++;
        }
    }
    int sz = ans.size();
    if(t < 10){
        cout << ans.size() << endl;
        for(int i = 0;i < sz;i++){
            cout << ans[i] << ' ';
        }
        cout << endl;
    }
}

signed main(){
    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
    int t = 0;
    cin >> t;
    for(int i = 1;i <= t;i++){
        solve(i,t);
    }
    return 0;
}