N = int(input())

ps = []
comp = [False] * (N + 1)
mu = [1] * (N + 1)
for i in range(2, N + 1):
	if not comp[i]:
		ps.append(i)
		mu[i] = -1
	
	for p in ps:
		if i * p > N:
			break
		comp[i * p] = True
		if i % p == 0:
			mu[i * p] = 0
			break
		mu[i * p] = mu[i] * -1

print(sum(mu[k] for k in range(1, N + 1)))