#include<bits/stdc++.h>
#define int long long
using namespace std;
int read()
{
	int x = 0, f = 1;
	char c = getchar();
	while(c != EOF and !isdigit(c))
	{
		if(c == '-')f = -1;
		c = getchar();
	}
	while(isdigit(c))
	{
		x = x * 10 + c - '0';
		c = getchar();
	}
	return x * f;
}
int n, m, k, w;
struct node{
	int p, c;
}a[200010];
bool cmp(node x, node y)
{
	return x.p < y.p;
}
vector<int>f;
vector<int>tmp;
bool solve(int as, int b)
{
	//cout<<as<<' '<<b<<endl;
	tmp.clear();
	int pos = a[as].p, i = as, res = 0;
	while(i <= b)
	{
		pos = a[i].p + k;
		//cout<<"pos"<<pos<<endl;
		if(pos > a[b+1].p)
		{
			sort(tmp.begin(), tmp.end());
			res = a[b+1].p - k;
			f.push_back(res);
			for(int j = tmp.size()-1;j >= 0;j --)
			{
				int s = tmp[j];
				if(a[s].p + k - 1 >= res)
				{
					res = res - k;
					f.push_back(res);
				}
				else{
					for(int q = 0;q <= j;q ++)f.push_back(a[tmp[q]].p);
					return true;
				}
				if(res <= a[as - 1].p)return false;
			}
			return true;
		}
		tmp.push_back(i);
		while(a[i].p < pos and i <= b)i ++;
		//cout<<"i"<<i<<endl;
	}
//	tmp.push_back();
	for(int q = 0;q < tmp.size();q ++)f.push_back(a[tmp[q]].p);
	return true;
}
signed main()
{
	int T = read();
	for(int t = 1;t <= T;t ++)
	{
		n = read();
		m = read();
		k = read();
		w = read();
		a[0]= {0, 2};
		a[n+m+1] = {w+1, 2};
		for(int i = 1;i <= n;i ++)
		{
			a[i].p = read();
			a[i].c = 1;
		}
		for(int i = 1;i <= m;i ++)
		{
			a[n+i].p = read();
			a[n+i].c = 2;
		}
//		if(t == 33)
//		{
//			cout<<n<<' '<<m<<' '<<k<' '<<w<<endl;
//			for(int i = 1;i <= n+m;i++)cout<<a[i].p<<' ';
//			cout<<endl;
//		}
		sort(a, a+n+m+2, cmp);
		int pos = 0, flag = 1;
		for(int i = 0;i <= n + m + 1;i ++)
		{
			if(a[i].c == 1)
			{
				if(pos == 0)
				{
					pos = i;
				}
			}
			else if(a[i].c == 2)
			{
				if(pos != 0)
				{
					if(pos == i - 1)
					{
						int d = a[i].p - a[pos - 1].p - 1;
						if(d < k)
						{
							//cout<<"why";
							flag = 0;
							break;
						}
						f.push_back(min(a[pos].p, a[i].p - k));
					}
					else 
					{
						//cout<<"fuck\n";
						if(! solve(pos, i-1))
						{
							flag = 0;
							break;
						}
						
					}
					pos = 0;
				}
			}
		}
		if(! flag)cout<<-1<<'\n';
		else 
		{
			sort(f.begin(), f.end());
			cout<<f.size()<<'\n';
			for(int i = 0;i < f.size();i ++)
			{
				cout<<f[i]<<' ';
			}
			cout<<endl;
		}
		for(int i= 0;i <= n+m+1;i ++)a[i] = {0, 0};
		f.clear();
	}
	return 0;
}