10707. 수도요금

solution 1

a,b,c,d,p = tuple(int(input()) for _ in range(5))
X = a*p
if p<=c:
    Y = b
else:
    Y = b + d*(p-c)
print(min(X,Y))

solution 2 : lambda 식

a,b,c,d,p = tuple(int(input()) for _ in range(5))
X = a*p
L = lambda b,c,d,p : b + d*(p-c) if p>c else b
print(min(X,L(b,c,d,p)))