from math import *

def Sieve(n):
    lst = [True] * (n + 1)
    S = set()
    for i in range(2, ceil(sqrt(n)) + 1):
        if lst[i]:
            for j in range(2 * i, n + 1, i):
                lst[j] = False
    for i in range(2, n + 1):
        if lst[i]:
            S.add(i)
    return S


N = int(input())
S = set()
prime_set= Sieve(N)
i = 1
while i * i <= N + 2:
    if i in prime_set:
        S.add(i * i)
    i += 1
    

ans = 1
for v in prime_set:
    if v == 2:
        continue
    if v + 2 in S:
        ans += 2
print(ans)