# https://yukicoder.me/problems/no/843



def main():
    N  = int(input())
    if N == 1:
        print(0)
        return

    prime_list = [True] * (N + 1)
    prime_list[1] = False
    primes = []
    for p in range(2, N + 1):
        if not prime_list[p]:
            continue

        primes.append(p)
        
        x = 2 * p
        while x <= N:
            prime_list[x] = False
            x += p

    odd_prime = [p for p in primes if p % 2 == 1]
    answer = 0

    # r == 2の場合
    for i in range(1, 4):
        j = 4 - i
        if i <= N and j <= N and prime_list[i] and prime_list[j]:
            answer += 1
    
    # r奇数の場合
    for r in odd_prime:
        if r ** 2 <= 2 * N:
            q = r ** 2 - 2
            if q <= N and prime_list[q]:
                answer += 2
    print(answer)

    










if __name__ == "__main__":
    main()