import abc
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, getmin=1, a_inc=0, x_inc=1):
        self.getmin = getmin
        self.a_inc = a_inc
        self.x_inc = x_inc
        self.ab = deque()
        self.inf = (1 << 63)-1
        self.px = self.inf*(-2*x_inc+1)

    def add_line(self, a, b):
        if not self.ab:
            self.ab.append((a, b))
            return
        # append
        if self.getmin ^ self.a_inc:
            if self.ab and a == self.ab[-1][0]:
                if (b-self.ab[-1][1])*(self.getmin*2-1) >= 0: return
                self.ab.pop()
            if self.x_inc:
                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
            else:
                (c, d), x = self.ab[-1], self.px
                if (a*x+b-c*x-d)*(self.getmin*2-1) >= 0: return
            self.ab.append((a, b))
        # appendleft
        else:
            if self.ab and a == self.ab[0][0]:
                if (b-self.ab[0][1])*(self.getmin*2-1) >= 0: return
                self.ab.popleft()
            if not self.x_inc:
                while len(self.ab) > 1:
                    c, d = self.ab.popleft()
                    e, f = self.ab[0]
                    if (b-d)*(e-c) < (d-f)*(c-a):
                        self.ab.append((c, d))
                        break
            else:
                (c, d), x = self.ab[0], self.px
                if (a*x+b-c*x-d)*(self.getmin*2-1) >= 0: return
            self.ab.appendleft((a, b))

    def __getitem__(self, x):
        if not self.ab: return self.inf*(self.getmin*2-1)
        if self.x_inc:
            while len(self.ab) > 1:
                a, b = self.ab.popleft()
                c, d = self.ab[0]
                if (a*x+b-c*x-d)*(self.getmin*2-1) < 0:
                    self.ab.appendleft((a, b))
                    return a*x+b
        else:
            while len(self.ab) > 1:
                a, b = self.ab.pop()
                c, d = self.ab[-1]
                if (a*x+b-c*x-d)*(self.getmin*2-1) < 0:
                    self.ab.append((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[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)