import sys

# sys.setrecursionlimit(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = (1 << 63)-1
# inf = (1 << 31)-1
# md = 10**9+7
md = 998244353

from collections import deque

# 最小値、傾き単調減少、x単調増加
class ConvexHullTrick:
    def __init__(self):
        self.ab = deque()

    def add_line(self, a, b):
        if self.ab and a == self.ab[-1][0]:
            if b >= self.ab[-1][1]: return
            self.ab.pop()
        while len(self.ab) > 1:
            c, d = self.ab.pop()
            e, f = self.ab[-1]
            if (b-d)*(e-c) > (d-f)*(c-a):
                self.ab.append((c, d))
                break
        self.ab.append((a, b))

    def min(self, x):
        if not self.ab: return (1 << 63)-1
        while len(self.ab) > 1:
            a, b = self.ab.popleft()
            c, d = self.ab[0]
            if a*x+b < c*x+d:
                self.ab.appendleft((a, b))
                return a*x+b
        a, b = self.ab[0]
        return a*x+b

n, a, b, w = LI()
dd = LI()

cht = ConvexHullTrick()
cht.add_line(0, 2*w)

ans = w+n*(n+1)//2*b-a*n
for i, d in enumerate(dd):
    cur = (cht.min(i)+i*(b*(i+1)-2*a)+2*d)//2
    r = n-i-1
    ans = min(ans, cur+r*(r+1)//2*b-a*r)
    i += 1
    cht.add_line(-2*b*i, 2*cur+i*(b*(i-1)+2*a))

print(ans)