a,b,c,d,e = input().split(" ")

a = int(a)
b = int(b)
c = int(c)
d = int(d)
e = int(e)

# 配る予定の数
candy_num = a * (b-c)

i = candy_num-1

X = d

if i==1:
    pass

elif i >=2:
    if i % 2 ==0:
        if(e <=X):
            X = X-e
        else:
            pass
    else:
        pass
        
print(candy_num*X)