//Author: Kevin
#include<bits/stdc++.h>
//#pragma GCC optimize("O2")
using namespace std;
#define ll long long
#define ull unsigned ll
#define pb emplace_back
#define mp make_pair
#define ALL(x) (x).begin(),(x).end()
#define rALL(x) (x).rbegin(),(x).rend()
#define srt(x) sort(ALL(x))
#define rev(x) reverse(ALL(x))
#define rsrt(x) sort(rALL(x))
#define sz(x) (int)(x.size())
#define inf 0x3f3f3f3f
#define pii pair<int,int>
#define lb(v,x) (int)(lower_bound(ALL(v),x)-v.begin())
#define ub(v,x) (int)(upper_bound(ALL(v),x)-v.begin())
#define uni(v) v.resize(unique(ALL(v))-v.begin())
#define longer __int128_t
void die(string S){puts(S.c_str());exit(0);}
int n,d,a,b;
int x[105];
int f[105][105],g[105][105];
int w[105][105][105];
int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>d>>a>>b;
	swap(a,b);
	for(int i=1;i<=n;i++)
	{
		cin>>x[i];
		x[i]-=d;
		x[i]*=a;
	}
	sort(x+1,x+n+1);
	d*=2*a;
	memset(f,0x3f,sizeof(f));
	memset(g,0x3f,sizeof(g));
	memset(w,0x3f,sizeof(w));
	for(int i=1;i<=n;i++)
		for(int j=i+1;j<=n;j++)
		{
			multiset<int> st;
			for(int p=i;p<=j;p++)
				st.insert(x[p]);
			int tot=0;
			auto it=next(st.begin());
			while(it!=st.end())
			{
				tot+=min(b,*it-*prev(it));
				it++;
			}
			for(int p=i;p<j;p++)
			{
				auto it=st.lower_bound(x[p]);
				if(next(it)!=st.end()) tot-=min(b,*next(it)-*it);
				if(it!=st.begin()) tot-=min(b,*it-*prev(it));
				if(next(it)!=st.end()) if(it!=st.begin()) tot+=min(b,*next(it)-*prev(it));
				st.erase(it);
				st.insert(x[p]+d);
				it=st.lower_bound(x[p]+d);
				if(next(it)!=st.end()) tot+=min(b,*next(it)-*it);
				if(it!=st.begin()) tot+=min(b,*it-*prev(it));
				if(next(it)!=st.end()) if(it!=st.begin()) tot-=min(b,*next(it)-*prev(it));
				w[i][p][j]=tot;
			}
		}
	for(int i=1;i<=n;i++)
		f[0][i]=0;
	for(int i=1;i<=n;i++)
		for(int j=0;j<i;j++)
		{
			for(int k=i+1;k<=n;k++)
				g[i][k]=min(g[i][k],f[j][i]+w[j+1][i][k]);
			for(int k=i+1;k<=n;k++)
			{
				int mx=max(x[j]+d,x[i]);
				int mn=min(x[i+1]+d,x[k+1]);
				f[i][k]=min(f[i][k],g[j][i]+min(b,max(0,mn-mx)));
			}
		}
	int ans=inf;
	for(int i=0;i<=n;i++)
		ans=min(ans,g[i][n]);
	int sum=0;
	for(int i=2;i<=n;i++)
		sum+=min(b,x[i]-x[i-1]);
	ans=min(ans,sum);
	cout<<ans+b<<'\n';
	return 0;
}