n = int(input())

counter = 0
for i in range(1, n + 1):
    if str(i)[-1] == 0 or str(i)[-1] == 5:
        if i % 3 == 0:
            counter += 4
        else:
            counter += 2
    elif i % 3 == 0:
        counter += 2

print(counter)