#include<iostream>
#include<algorithm>
using namespace std;
const int size=1e5+10;
int n;
int d[size];
int x,y;
int dist;

int main()
{
	cin >> n;
	for(int i=0;i<n;i++)cin >> d[i];
	cin >> x >> y;
	
	dist=abs(x)+abs(y);
	//0
	if(x==0 && y==0)
	{
		cout << 0 << endl;
		return 0;
	}
	
	//1
	for(int i=0;i<n;i++)
	{
		if(dist==d[i])
		{
			cout << 1 << endl;
			return 0;
		}
	}
	
	//2
	sort(d,d+n,greater<int>());
	for(int i=0;i<n;i++)
	{
		if(d[i]>dist)continue;
		for(int j=i;j<n;j++)
		{
			if(d[i]+d[j]==dist)
			{
				cout << 2 << endl;
				return 0;
			}
			if(d[i]+d[j]<dist)break;
		}
	}
	
	cout << -1 << endl;
	return 0;
}