n = int(input())
prime = [True for _ in range(n + 1)]
prime[0] = prime[1] = False
for i in range(2, int(n ** 0.5) + 1):
    if not prime[i]:
        continue
    for j in range(i * i, n + 1, i):
        prime[j] = False
prime_lst = []
for i in range(n + 1):
    if prime[i]:
        prime_lst.append(i)

ans = 0
p = 2
for q in prime_lst:
    rr = p + q
    r = int(rr ** 0.5)
    if r ** 2 != rr:
        continue
    elif prime[r]:
        ans += 2
        if p == q == 2:
            ans -= 1
            
print(ans)