def era(n):
    is_prime = [True]*(n+1)
    is_prime[0] = False
    is_prime[1] = False
    
    for i in range(2, int(n**0.5)+1):
        if not is_prime[i]:
            continue
        
        for j in range(2*i, n+1, i):
            is_prime[j] = False
    
    return is_prime, [i for i in range(n+1) if is_prime[i]]

N = int(input())
is_prime, primes = era(N)
ans = 0

for r in primes:
    if r**2>2*N:
        break
    
    for p in primes:
        if r**2-p<0:
            break
        
        if r**2-p<=N and is_prime[r**2-p]:
            ans += 1

print(ans)