N = int(input())


def eratosthenes(n):
    is_primes = [True] * n
    for x in range(2, int(n ** 0.5) + 1):
        if is_primes[x]:
            for mx in range(2 * x, n, x):
                is_primes[mx] = False

    return [i for i in range(2, n) if is_primes[i]]


primes = eratosthenes(N)
prime_set = set(primes)
r_candidates = [int(n ** 0.5) for n in range(2, N + 1) if (n ** 0.5) in prime_set]

ans = 0
for r in r_candidates:
    for p in primes:
        q = r ** 2 - p
        if q in prime_set:
            ans += 1

print(ans)