#include"bits/stdc++.h"

#define mid (l + ((r - l) >> 1))

using namespace std;

const long long N = 1e6 + 10;

long long sum[N << 3], ls[N << 3], rs[N << 3], root, cnt, a[N << 3];

void push_up(long long i) {
	sum[i] = sum[ls[i]] + sum[rs[i]];
	a[i] = a[ls[i]] + a[rs[i]];
}

void add(long long &i, long long l, long long r, long long pos, long long vol) {
	if(!i) i = ++cnt;
	if(l == r) {
		sum[i] += l * vol;
		a[i] += vol;
		return ;
	}
	else if(pos <= mid) add(ls[i], l, mid, pos, vol);
	else add(rs[i], mid + 1, r, pos, vol);
	push_up(i);
}

long long query1(long long i, long long l, long long r, long long vol) {
	//cout << l << " " << r << " " << mid << " " << a[i] << " " << vol << "\n";
	//cout << a[ls[i]] << " " << a[rs[i]] << "\n";
	//cout << sum[ls[i]] << " " << sum[rs[i]] << "\n";
	if(l == r) return vol * l;
	else if(vol <= a[rs[i]]) return query1(rs[i], mid + 1, r, vol);
	else return query1(ls[i], l, mid, vol - a[rs[i]]) + sum[rs[i]];
}

long long query2(long long i, long long l, long long r) {
	if(l == r) return l;
	else if(a[ls[i]]) return query2(ls[i], l, mid);
	else return query2(rs[i], mid + 1, r);
}

long long query3(long long i, long long l, long long r, long long k) {
	// cout << l << " " << r << " " << mid << " " << a[i] << " " << k << "\n";
	// cout << a[ls[i]] << " " << a[rs[i]] << "\n";
	// cout << sum[ls[i]] << " " << sum[rs[i]] << "\n";
	if(l == r) return l;
	else if(k <= a[ls[i]]) return query3(ls[i], l, mid, k);
	else return query3(rs[i], mid + 1, r, k - a[ls[i]]);
}

long long b[N];

void solve() {
	root = 0;
	long long n, m;
	cin >> n >> m;
	vector<long long> ans;
	for(long long i = 1; i <= n; i++) {
		long long x;
		cin >> x;
		add(root, 1, 1e9 + 10, x, 1);
	}
	long long sum = 0;
	for(long long i = 1; i <= m; i++) {
		cin >> b[i];
		sum += b[i];
		if(query3(root, 1, 1e9 + 10, n - m + i) > b[i]) {
			cout << -1 << "\n";
			return ;
		}
	}
	// if(sum - query1(root, 1, 1e9 + 10, m) > a[root] - m) {
	// 	cout << "-1" << "\n";
	// 	return ;
	// }
	long long kk = 0;
	sort(b + 1, b + 1 + m);
	while(kk < n - m && sum - query1(root, 1, 1e9 + 10, m) != a[root] - m) {
		long long now = query2(root, 1, 1e9 + 10);
		ans.push_back(now);
		add(root, 1, 1e9 + 10, now, -1);
		add(root, 1, 1e9 + 10, now + 1, 1);
		add(root, 1, 1e9 + 10, query2(root, 1, 1e9 + 10), -1);
		kk++;
	}
	//cout << kk << "\n";
	for(long long i = m; i >= 1; i--) {
		if(kk >= n - m) break;
		//cout << "$$$$$" << a[root] - m + i << "\n";
 		long long ai = query3(root, 1, 1e9 + 10, a[root] - m + i);
		//cout << i << " " << ai << " " << b[i] << "\n";
		if(ai > b[i]) {
			cout << -1 << "\n";
			return ;
		}
		while(ai < b[i]) {
			ans.push_back(ai);
			add(root, 1, 1e9 + 10, ai, -1);
			add(root, 1, 1e9 + 10, ai + 1, 1);
			//cout << "###" << query2(root, 1, 1e9 + 10) << "\n";
			add(root, 1, 1e9 + 10, query2(root, 1, 1e9 + 10), -1);
			ai++;
			kk++;
		}
	}
	for(long long i = 1; i <= m; i++) {
		//cout << query3(root, 1, 1e9 + 10, a[root] - m + i) << " " << b[i] << "\n";
		if(query3(root, 1, 1e9 + 10, a[root] - m + i) != b[i]) {
			cout << "-1" << "\n";
			return ;
		}
	}
	cout << n - m << "\n";
	for(auto i : ans) cout << i << " ";
	cout << "\n";
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0), cout.tie(0);
	long long t;
	cin >> t;
	while(t--) solve();
	return 0;
}