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

using VI = vector<int>;
using VVI = vector<VI>;
using PII = pair<int, int>;
using LL = long long;
using VL = vector<LL>;
using VVL = vector<VL>;
using PLL = pair<LL, LL>;
using VS = vector<string>;

#define ALL(a)  begin((a)),end((a))
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define SZ(a) int((a).size())
#define SORT(c) sort(ALL((c)))
#define RSORT(c) sort(RALL((c)))
#define UNIQ(c) (c).erase(unique(ALL((c))), end((c)))

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

#define FF first
#define SS second

#define DUMP(x) cout<<#x<<":"<<(x)<<endl
template<class S, class T>
istream& operator>>(istream& is, pair<S,T>& p){
  return is >> p.FF >> p.SS;
}
template<class T>
istream& operator>>(istream& is, vector<T>& xs){
  for(auto& x: xs)
	is >> x;
  return is;
}
template<class S, class T>
ostream& operator<<(ostream& os, const pair<S,T>& p){
  return os << p.FF << " " << p.SS;
}
template<class T>
ostream& operator<<(ostream& os, const vector<T>& xs){
  for(unsigned int i=0;i<xs.size();++i)
	os << (i?" ":"") << xs[i];
  return os;
}
template<class T>
void maxi(T& x, T y){
  if(x < y) x = y;
}
template<class T>
void mini(T& x, T y){
  if(x > y) x = y;
}


const double EPS = 1e-10;
const double PI  = acos(-1.0);
const LL MOD = 1e9+7;


template<class T>
struct ConvexHullTrick{
  using Line = pair<T,T>;
  deque<Line> lines;
  
  ConvexHullTrick(){
	//lines.emplace_back(0, 0);
  }
 
  bool check(Line l1, Line l2, Line l3){
	if(l1 < l3) swap(l1, l3);
	return (l3.SS - l2.SS) * (l2.FF - l1.FF) >= (l2.SS - l1.SS) * (l3.FF - l2.FF);
  }
 
  // y = ax + b
  void add(T a, T b){
	Line l(a, b);
	while(lines.size() >= 2 && check(*(lines.end()-2), *(lines.end()-1), l))
	  lines.pop_back();
	lines.emplace_back(l);
  }
 
  T f(Line l, T x){
	return l.FF * x + l.SS;
  }
 
  T getmin(T x){
	int lb = -1, ub = lines.size()-1;
	while(ub-lb > 1){
	  int m = (lb + ub) / 2;
	  (f(lines[m], x) > f(lines[m+1], x)? lb: ub) = m;
	}
	return f(lines[ub], x);
  }
};

int main(){
  cin.tie(0);
  ios_base::sync_with_stdio(false);

  LL N, A, B, W;
  cin >> N >> A >> B >> W;

  VL ds(N+1);
  cin >> ds;

  VL dp(N+1, 1e18);
  ConvexHullTrick<LL> cht;

  LL ans = N*(N+1)/2*B - N*A;
  for(LL i=1;i<=N;++i){
	dp[i] = i * (i+1) / 2 * B - i*A + ds[i];
	if(i>1)
	  mini(dp[i], ds[i] - (i-1)*A + (i*i-i)/2*B + cht.getmin(i));

	cht.add(-B * i, dp[i] + i*A + i*(i+1)/2*B);
	mini(ans, dp[i] + (N-i-1)*(N-i)/2*B - (N-i-1)*A);
  }

  cout << ans+W << endl;

  return 0;
}