from fractions import gcd
from datetime import date
from math import factorial
import functools
from heapq import*
from collections import deque
import collections
import math
from collections import defaultdict, Counter
import sys
sys.setrecursionlimit(10 ** 7)
MOD = 10 ** 9 + 7
inf = float("inf")


def primes(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(i * 2, n + 1, i):
            is_prime[j] = False
    return [i for i in range(n + 1) if is_prime[i]]


def is_prime(n):
    if n == 1:
        return False

    for k in range(2, int(math.sqrt(n)) + 1):
        if n % k == 0:
            return False

    return True


def main():
    n = int(input())
    l = primes(n)
    ans = 0
    for j in l:
        if j ** 2 - 2 <= 0 or j ** 2 - 2 > n:
            continue
        if is_prime(j ** 2 - 2):
            if j == 2:
                ans += 1
            else:
                ans += 2
    print(ans)


if __name__ == '__main__':
    main()