from itertools import chain


def prime_set(N):
    """
    Nまでの素数のsetを返す
    """
    if N < 4:
        return ({}, {}, {2}, {2, 3})[N]
    Nsq = int(N ** 0.5 + 0.5) + 1
    primes = {2, 3} | set(chain(range(5, N + 1, 6), range(7, N + 1, 6)))
    for i in range(5, Nsq, 2):
        if i in primes:
            primes -= set(range(i * i, N + 1, i * 2))
    return primes


N = int(input())
R = []
prime = prime_set(N)
for p in prime:
    if p * p < N:
        R.append(p*p)

ans = 0
for p in prime:
    for r in R:
        q = r - p
        if p <= q and q in prime:
            if p == q:
                ans += 1
            else:
                ans += 2
print(ans)