#include <bits/stdc++.h>
#define REP(i,n,N) for(int i=(n);i<(int)N;i++)
#define p(s) cout<<(s)<<endl
using namespace std;

int main(){
	int n,x,y;
	cin>>n;
	int d[16];
	int idou=0;
	REP(i,0,n) {
		cin>>d[i];
		idou=max(idou,d[i]);
	}
	cin>>x>>y;
	int ans=-1;
	int goal=max(abs(x),abs(y));
	if(goal==0) ans=0;
	if(ans<0) REP(i,0,n) if(goal == d[i]) ans=1;
	if(ans<0)for(ans=2;goal>idou*ans;ans++)	;
	p(ans);
	return 0;
}