import math

def count_triple_primes(N):
    if N < 2:
        return 0

    # Sieve of Eratosthenes up to N
    is_prime = [True] * (N + 1)
    is_prime[0], is_prime[1] = False, False
    for i in range(2, int(math.isqrt(N)) + 1):
        if is_prime[i]:
            for j in range(i * i, N + 1, i):
                is_prime[j] = False

    count = 0

    # Check r=2 case
    if N >= 2 and 4 <= 2 * N:
        count += 1

    # Check odd primes r where r^2 <= N + 2
    max_r = math.isqrt(N + 2)
    for r in range(3, max_r + 1, 2):
        if is_prime[r]:
            r_squared = r * r
            q = r_squared - 2
            if q >= 2 and q <= N and is_prime[q]:
                count += 2

    return count

# Read input and output the result
N = int(input())
print(count_triple_primes(N))