from typing import Sequence


def is_prime(num: int, prime_list: Sequence[int]) -> bool:
    return all(num % prime for prime in prime_list if prime < num)


def main():
    N = int(input())

    prime_numbers = []
    for number in range(2, 10**3):
        for prime in prime_numbers:
            if number % prime == 0:
                break
        else:
            prime_numbers.append(number)

    patterns = 0
    for prime in prime_numbers:
        if prime > N:
            break

        if is_prime(q := (prime ** 2 - 2), prime_numbers):
            if q > N:
                break
            if prime == 2:
                patterns += 1
            else:
                patterns += 2

    print(patterns)


if __name__ == "__main__":
    main()