#include<cstdio>
#include<vector>
#include<algorithm>


using namespace std;
using vi=vector<int>;


int solve_r(vi& a, vi& b, int d)
{
	if(d>=a.size())
	{
		return 1;
	}

	for(int i=0;i<b.size();i++)
	{
		if(a[d]>b[i]) continue;

		b[i]-=a[d];
		if(solve_r(a, b, d+1)) return 1;
		b[i]+=a[d];
	}
	return 0;
}


int solve(vi& a, vi b)
{
	vi c;

	for(int i=1;i<=b.size();i++)
	{
		c=b;
		c.resize(i);
		if(solve_r(a, c, 0)) return i;
	}

	return -1;
}


int main(void)
{
	int  n, m, i;
	vi a, b;

	while(scanf("%d", &n)==1)
	{
		a.resize(n);
		for(i=0;i<n;i++) scanf("%d", &a[i]);

		scanf("%d", &m);
		b.resize(m);
		for(i=0;i<m;i++) scanf("%d", &b[i]);

		sort(a.begin(), a.end(), greater<int>());
		sort(b.begin(), b.end(), greater<int>());
		printf("%d\n", solve(a, b));
	}

	return 0;
}