N = int(input())


def eratosthenes(n):
    if n < 2:
        return []

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

    return [i for i in range(2, n + 1) if is_primes[i]]


primes = eratosthenes(N)
prime_set = set(primes)

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

print(ans)