N = int(input())

lp = [-1] * (N + 1)
mu = [1] * (N + 1)
for i in range(2, N + 1):
	if lp[i] == -1:
		for j in range(i, N + 1, i):
			lp[j] = i
	
	if i % (lp[i] * lp[i]) == 0:
		mu[i] = 0
	else:
		mu[i] = mu[i // lp[i]] * -1

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