#include<bits/stdc++.h>
using namespace std;

#define int long long
typedef vector<int>vint;
typedef pair<int,int>pint;
typedef vector<pint>vpint;
#define rep(i,n) for(int i=0;i<(n);i++)
#define reps(i,f,n) for(int i=(f);i<(n);i++)
#define all(v) (v).begin(),(v).end()
#define each(it,v) for(__typeof((v).begin()) it=(v).begin();it!=(v).end();it++)
#define pb push_back
#define mp make_pair
#define fi first
#define se second
template<typename A,typename B>inline void chmin(A &a,B b){if(a>b)a=b;}
template<typename A,typename B>inline void chmax(A &a,B b){if(a<b)a=b;}

typedef long long ll;
struct ConvexHullTrick {
	vector<pair<ll, ll>> ls; // slope, intercept

	bool check(pair<ll, ll> l1, pair<ll, ll> l2, pair<ll, ll> l3) {
		return (l2.first - l1.first) * (l3.second - l2.second) >= (l2.second - l1.second) * (l3.first - l2.first);
	}

	void add(ll a, ll b) {
		pair<ll, ll> l(a, b);
		while (ls.size() >= 2 && check(ls[ls.size() - 2], ls[ls.size() - 1], l)) ls.pop_back();
		ls.emplace_back(l);
	}

	ll f(int k, ll x) {
		return ls[k].first * x + ls[k].second;
	}

	ll query(ll x) {
		int low = -1;
		int high = ls.size() - 1;
		while (high - low > 1) {
			int mid = (low + high) / 2;
			(f(mid, x) <= f(mid + 1, x) ? low : high) = mid;
		}
		return f(high, x);
	}
};

int N,A,B,W;
int D[300000];

signed main(){
    cin>>N>>A>>B>>W;
    rep(i,N)cin>>D[i];

    W-=A*N;
    W+=B*N*(N+1)/2;

    int mi=0;

    ConvexHullTrick cht;
    cht.add(0,0);
    rep(i,N){
        int t=-cht.query(i)+D[i]+A-(N-i)*(i+1)*B;
        chmin(mi,t);
        cht.add((i+1)*B,-t-B*N*(i+1));
    }

    cout<<mi+W<<endl;
    return 0;
}