#include<iostream>
#include<queue>
#include<map>
#include<set>
#include<vector>
#include<algorithm>
#include<deque>
#include<cctype>
#include<string.h>
#include<math.h>
#include<time.h>
#include<random>
#include<stack>
#include<string>
#define ll                                     long long
#define lowbit(x) (x & -x)
#define endl "\n"//                           交互题记得删除
using namespace std;
mt19937 rnd(time(0));
const ll mod = 998244353;
ll ksm(ll x, ll y)
{
	ll ans = 1;
	while (y)
	{
		if (y & 1)
		{
			ans = ans % mod * (x % mod) % mod;
		}
		x = x % mod * (x % mod) % mod;
		y >>= 1;
	}
	return ans % mod % mod;
}
ll gcd(ll x, ll y)
{
	if (y == 0)
		return x;
	else
		return gcd(y, x % y);
}
void fio()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
}
ll a[450000];
ll b[450000];
vector<ll> ans;
ll d[450000];
int main()
{
	fio();
	ll t;
	cin >> t;
	while (t--)
	{
		ans.clear();
		ll n, m, k, w;
		cin >> n >> m >> k >> w;
		for (ll i = 1; i <= n; i++)
		{
			cin >> a[i];
		}
		for (ll i = 1; i <= m; i++)cin >> b[i];
		b[m + 1] = w + 1;
		b[0] = 0;
		sort(a + 1, a + 1 + n);
		sort(b + 1, b + 1 + m);
		ll l,r;
		ll cnt=1;
		ll pd=0;
		for(ll i=0;i<=m;i++)
		{
			l=r=cnt;
			if(cnt==n+1)break;
			if(b[i+1]<a[r])continue;
			while(a[cnt]>=b[i]&&a[cnt]<=b[i+1])
			{
				r=cnt;
				cnt++;
			}
			ll op=0;
			for(ll j=l;j<=r;j++)
			{
				if(j==l)
				{
					op++;
					d[op]=a[j];
				}
				else 
				{
					if(a[j]<=d[op]+k-1)continue;
					else 
					{
						op++;
						d[op]=a[j];
					}
				}
			}
			d[op+1]=b[i+1];
			//cout<<b[i+1]<<endl;
			for(ll j=op;j>=1;j--)
			{
				if(d[j]+k-1>=d[j+1])
				{
					ll u=d[j+1]-(k-1)-1;
					d[j]=u;
				}
				else 
				continue;
			}
			//cout<<d[1]<<" "<<d[2]<<" "<<d[3]<<endl;
			if(d[1]<=b[i]&&d[1]+k-1>=a[l])
			{
				pd=1;
				break;
			}
			else 
			{
				ll u=l;
				for(ll j=1;j<=op;j++)
				{
					ll of=0;
					while(a[u]>=d[j]&&a[u]<=d[j]+k-1)
					{
						u++;
						of=1;
					}
					if(of)
					ans.push_back(d[j]);
				}
			}
		}
		if(pd)
		cout<<-1<<endl;
		else 
		{
			cout<<ans.size()<<endl;
			for(auto j:ans)
			cout<<j<<" ";
			cout<<endl;
		}
	}
}