#include <iostream>
#include <cstring>
#include <cmath>
#include <cstdlib>
#include <cstdio>

using namespace std;

int n,a[51],l,r,ans;

int main()
{
	freopen("groupa.in","r",stdin);
	freopen("groupa.out","w",stdout);
	scanf("%d",&n);
	for (int i=1;i<=n;i++)
	{
		scanf("%d",a+i);
	}
	scanf("%d%d",&l,&r);
	
	for (int i=1;i<=n;i++)
	{
		for (int j=i+1;j<=n && a[i]>r;j++)
		if (a[j]<l) 
		{
			int t=min(l-a[j],a[i]-r);
			a[i]-=t;
			a[j]+=t;
			ans+=t;
		}
		for (int j=1;j<=n && a[i]>r;j++)
		if (a[j]<r)
		{
			int t=min(r-a[j],a[i]-r);
			a[i]-=t;
			a[j]+=t;
			ans+=t;
		}
		
		for (int j=i+1;j<=n && a[i]<l;j++)
		if (a[j]>r) 
		{
			int t=min(a[j]-r,l-a[i]);
			a[i]+=t;
			a[j]-=t;
			ans+=t;
		}
		for (int j=1;j<=n && a[i]<l;j++)
		if (a[j]>l)
		{
			int t=min(a[j]-l,l-a[i]);
			a[i]+=t;
			a[j]-=t;
			ans+=t;
		}
		if (a[i]>r || a[i]<l) {ans=-1;break;}
	}
	printf("%d\n",ans);
	return 0;
}