deli, calory, becon, deli_per_be, calo_per_be = list(map(int, input().split()))
utility = deli - calory
for n in becon:
	if deli + n*deli_per_be - n*calo_per_be - calory > utility:
		utility = deli + n*deli_per_be - n*calo_per_be - calory
print(utility)