#include<bits/stdc++.h>
using namespace std;
int n,a[60],sum1=0,sum2=0,sum3=0,sum4=0,l,r;
int main(){
    cin>>n;
    for(int i=1;i<=n;i++)
        cin>>a[i];
    cin>>l>>r;
    sort(a+1,a+1+n);
    for(int i=1;i<=n;i++){
    	if(a[i]<l)
    	    sum1+=l-a[i];
    	else if(a[i]>r)
    	    sum2+=a[i]-r;
    	else{
    		sum3+=a[i]-l;
    		sum4+=r-a[i];
		}
	}
	if(sum1>sum2){
		if(sum1-sum2>sum3)
		    cout<<-1;
		else
		    cout<<sum1;
	}else{
		if(sum2-sum1>sum4)
		    cout<<-1;
		else
		    cout<<sum2;
	}
    return 0;
}