#include<bits/stdc++.h>
using namespace std;
#define int long long
const int N=1e6+10,INF=1e18+10,K=1030;
inline int read(){int x=0,f=1;char ch=getchar();while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){x=(x<<3)+(x<<1)+ch-48;ch=getchar();}return x*f;}
int n,a,b,w,ans=INF,d[N],f[K],g[K];
signed main(){
	n=read(),a=read(),b=read(),w=read();
	for(int i=1;i<=n;i++) d[i]=read();
	if(b==0){
		cout<<w-n*a<<'\n';
		return 0;
	}else{
		int lim=ceil(pow(a/b,0.5))+100;
		lim=min(lim,1010ll);
		memset(f,0x3f,sizeof(f));
		f[0]=w;
		for(int i=1;i<=n;i++){
//			for(int j=0;j<=lim+10;j++) g[j]=INF;
			memset(g,0x3f,sizeof(g));
			for(int j=0;j<=lim;j++){
				g[j+1]=min(g[j+1],f[j]+b*(j+1)-a);
				g[0]=min(g[0],f[j]+d[i]);
			}
			swap(f,g);
		}
		for(int i=0;i<=lim;i++) ans=min(ans,f[i]);
		cout<<ans<<'\n';
	}return 0;
}