N = int(input())
cur = 1

limit = 10**3
distinct_prime_factor_count = [0]*(limit+1)
primes = []
for i in range(2, limit+1):
    if distinct_prime_factor_count[i] == 0:
        primes.append(i)
        for num in range(i, limit+1, i):
            distinct_prime_factor_count[num] += 1

cnt = 0
for prime in primes:
    # prime を掛けて N を超えたら break
    if cur * prime > N:
        break
    else:
        cur *= prime
        cnt += 1

print(cnt)