def primes(n):
    ps = [2]
    t = [True] * (n + 1)
    for i in range(3, n+1, 2):
        if t[i]:
            ps.append(i)
            for j in range(i+i, n+1, i):
                t[j] = False
    return ps


N = int(input())

ps = primes(1000)
x = 1
ans = 0
for p in ps:
    if x*p > N: break
    x *= p
    ans += 1

print(ans)