#include<iostream>
#include<cstdio>
#include<cstring>
#include<map>
#include<cmath>
#include<queue>
#include<algorithm>
#include<vector>
using namespace std;
long long n,a[77],l,r,ji,he;
long long ans=0,minn;
int main()
{
  cin>>n;
  for(int i=1;i<=n;i++)
  {
  	cin>>a[i];
  	he+=a[i];
  }
  cin>>l>>r;
  if(l>=r||he>r*n||he<r*n)
  {
  	cout<<"-1"<<endl; 
      return 0;
  }
  for(int i=1;i<=n;i++)
  {
  	if(a[i]>r)
  	{
  		ji=a[i]-r;
  		if(ji<minn);
  		{
  			minn=ji;
		}
		ji=0;
	}
	  	if(a[i]<l)
  	{
  		ji=l-a[i];
  		if(ji<minn);
  		{
  			minn=ji;
		}
		ji=0;
	}
  }
  cout<<minn<<endl;
}