#include<bits/stdc++.h>
 using namespace std;
#define INF 1000000000
#define REP(i,n) for(int (i)=0;(i)<(int)(n);(i)++)
typedef long long LL;
int N,A,B,W;
int D[300011];
int sum[300011];
LL que[300011];
LL day[300011];

void calc_sum(){
     sum[0]=0;
     REP(i,300010){
        sum[i+1]=sum[i]-A+B*(i+1);
     }
}

LL change(LL q1,LL d1,LL q2,LL d2){
   q1+=sum[(d2-d1)];
   if(B<=A)return 1e12;
   if(B==0)return 1e12;
   LL btk=q2-q1;
   
   return btk/(B*(d2-d1))+1+d2;
}

int main(){
    cin>>N>>A>>B>>W;
    calc_sum();
    REP(i,N){
       cin>>D[i+1];
    }
   /* REP(i,N+1){
        printf("sum[%d]=%d",i,sum[i]);
    }*/
    que[0]=0;
    day[0]=0;
    int l=0,r=1;
    REP(i,N+1){
        if(i==0)continue;
        int n_day=i;
        //先頭の更新
        while(1){
           if(r-l==1)break;//queに要素が1つ
           if(change(que[l],day[l],que[l+1],day[l+1])<n_day){
              //printf("change%d\n",change(que[l],day[l],que[l+1],day[l+1]));
             // printf("l,que=%d,day=%d,\n",que[l],day[l]);
              l++;

           }else{
              //printf("change%d\n",change(que[l],day[l],que[l+1],day[l+1]));
              //printf("l,day=%dday2=%d,\n",day[l],day[l+1]);
              break;
           }
        }
        //後ろに追加
        que[r]=que[l]+sum[n_day-day[l]-1]+D[n_day];//これを後ろに追加
        day[r]=n_day;
       // cout<<"ok"<<endl;
        //後ろの更新
        while(1){
            if(r-l==0)break;
            if(r-l==1)break;
            if(change(que[r-1],day[r-1],que[r],day[r])<change(que[r-2],day[r-2],que[r-1],day[r-1])){
               //printf("r,que=%d,day=%d\n",que[r-1],day[r-1]);
               que[r-1]=que[r];
               day[r-1]=day[r];
               r--;
            }else{
               break;
            }
        }
        r++;
    }
    //残ったもので計算
    LL ans=1e17;
    //printf("l=%d,r=%d\n",l,r);
    for(int i=l;i<r;i++){
        //cout<<que[i]<<" "<<day[i]<<endl;
        ans=min(ans,que[i]+sum[N-day[i]]);
    }
    //cout<<ans<<endl;
    cout<<ans+W<<endl;
    return 0;
}