#include <bits/stdc++.h>
#include <cstdio>
#include <string>

using namespace std;

#define INF 100000000
#define YJ 1145141919
#define INF_INT_MAX 2147483647
#define INF_LL_MAX 9223372036854775807
#define EPS 1e-10
#define MOD 1000000007
#define Pi acos(-1)
#define LL long long
#define ULL unsigned long long
#define LD long double

#define int long long

template< class T >
struct ConvexHullTrickAddQueryMonotone
{
  deque< pair< T, T > > L;
  int isdec;
 
  ConvexHullTrickAddQueryMonotone() : isdec(-1) {}
 
  inline T getX(const pair< T, T > &a, const T &x)
  {
    return (a.first * x + a.second);
  }
 
  inline bool check(const pair< T, T > &a, const pair< T, T > &b, const pair< T, T > &c)
  {
    return ((b.first - a.first) * (c.second - b.second) >= (b.second - a.second) * (c.first - b.first));
  }
 
  inline bool empty() { return (L.empty()); }
 
  void add(T a, T b)
  {
    pair< T, T > line(a, b);
 
    if(!L.empty() && L.back().first == a) {
      line.second = min(line.second, L.back().second);
      L.pop_back();
    }
    while(L.size() >= 2 && check(L[L.size() - 2], L.back(), line)) L.pop_back();
    L.emplace_back(line);
 
  }
 
  T getMinimumQuery(T x)
  {
    int low = -1, high = (int) L.size() - 1;
    while(high - low > 1) {
      int mid = (low + high) >> 1;
      if((getX(L[mid], x) >= getX(L[mid + 1], x))) low = mid;
      else high = mid;
    }
    return (getX(L[high], x));
  }
 
  T getMinimumQueryMonotone(T x)
  {
    while(L.size() >= 2 && getX(L[0], x) >= getX(L[1], x)) {
      L.pop_front();
    }
    return (getX(L[0], x));
  }
 
};

const int MAX_N = 300005;
int N, A, B, W;
int D[MAX_N];
int dp[MAX_N];

signed main()
{
  cin >> N >> A >> B >> W;
  for(int i = 0; i < N; i++) {
    cin >> D[i];
  }

  dp[0] = 0;
  
  ConvexHullTrickAddQueryMonotone<int> cht;

  cht.add(0, 0);

  for(int i = 1; i <= N; i++) {
    dp[i] = cht.getMinimumQueryMonotone(i) - A*(i-1) + (i-1)*i/2*B + D[i-1];
    cht.add(-i*B, dp[i] + i*A + (i+1)*i/2*B);
    //cerr << dp[i] << " " << cht.get(i-1) << " " << D[i-1] << endl;
  }

  int ans = 114514191981036436;
  for(int i = 0; i < N+1; i++) {
    //cerr << i << " " << dp[i] << endl;
    ans = min(ans, dp[i] + (-(N-i)*A + (N-i)*(N-i+1)/2*B));
  }

  cout << ans+W << endl;

  return 0;
}