#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
int a[55],x,y,sum;
int  main()
{
	freopen("groupa.in","r",stdin);
	freopen("groupa.out","w",stdout);	
	int n;
	scanf("%d",&n);
	for(int i=1;i<=n;i++)
		scanf("%d",&a[i]),sum+=a[i];
	int l,r;
	scanf("%d%d",&l,&r);
	for(int i=1;i<=n;i++)
	{
		if(a[i]>r)x+=a[i]-r;
		if(a[i]<l)y+=l-a[i];
	}
	if(n*r<sum||n*l>sum){
		printf("-1");
		return 0;
	}
	int ans=max(x,y);
	printf("%d",ans);
	return 0;
}