import sys
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
def LI2(): return list(map(int,sys.stdin.readline().rstrip()))
def S(): return sys.stdin.readline().rstrip()
def LS(): return list(sys.stdin.readline().rstrip().split())
def LS2(): return list(sys.stdin.readline().rstrip())


class LiChao_tree():
    def __init__(self,X):  # Xに属する点における最小値を考える
        X = sorted(set(X))
        self.inf = 1 << 61
        self.N = 1 << (len(X)-1).bit_length()
        self.X = X+[self.inf]*(self.N-len(X))
        self.tree = [None]*(self.N << 1)
        self.X_dict = {x: i for i,x in enumerate(X)}

    def get_val(self,a,b,x):
        return a*x+b

    def add_line(self,a,b):  # 直線ax+bの追加
        i = 1
        left,right = 0,self.N
        while left < right:
            if self.tree[i] is None:
                self.tree[i] = (a,b)
                return
            mid = (left+right) >> 1
            x_left,x_mid,x_right = self.X[left],self.X[mid],self.X[right-1]
            ai,bi = self.tree[i]
            comp_left = self.get_val(a,b,x_left) < self.get_val(ai,bi,x_left)
            comp_mid = self.get_val(a,b,x_mid) < self.get_val(ai,bi,x_mid)
            comp_right = self.get_val(a,b,x_right) < self.get_val(ai,bi,x_right)

            if comp_left == comp_right:
                if comp_left:
                    self.tree[i] = (a,b)
                return
            if comp_mid:
                self.tree[i],a,b = (a,b),ai,bi
            if comp_left != comp_mid:
                i,right = i << 1,mid
            else:
                i,left = i << 1 | 1,mid

    def get_min(self,x):  # xにおける最小値を返す
        i = self.X_dict[x]+self.N
        res = self.inf
        while i:
            if self.tree[i] is not None:
                a,b = self.tree[i]
                res = min(res,self.get_val(a,b,x))
            i >>= 1
        return res


N,A,B,W = MI()
D = [0]+LI()

X = [i for i in range(1,N+1)]
LCT = LiChao_tree(X)
inf = 10**18
dp = [inf]*(N+1)  # dp[i] = i日目にドーナツを食べる
dp[0] = 0
LCT.add_line(0,0)
for i in range(1,N+1):
    dp[i] = D[i]+(B*i*(i-1))//2-A*(i-1)+LCT.get_min(i)
    LCT.add_line(-B*i,A*i+(B*(i**2+i))//2+dp[i])

ans = W+min(dp[i]-A*(N-i)+(B*(N-i)*(N-i+1))//2 for i in range(N+1))
print(ans)