A, B, C, D, E = map(int, input().split())


n = B - C

if n == 0:
    print(0)
    exit()
if n == 1:
    print(D)
    exit()

    
acc = D
x = D
for i in range(1, n):
    if i%10 != 0:
        acc += x
    elif i%10 == 0 and x > E:
        x -= E
        acc += x
    elif i%10 == 0 and x < E:
        acc += x

print(acc)