MOD = 10 ** 9 + 7
INF = 10 ** 20
import sys
input = sys.stdin.readline
sys.setrecursionlimit(100000000)
from collections import defaultdict
dy = (-1,0,1,0)
dx = (0,1,0,-1)

def sieve(n):
    prime = []
    limit = n ** 0.5
    data = [i + 1 for i in range(1,n)]
    while True:
        p = data[0]
        if limit <= p:
            return prime + data
        prime.append(p)
        data = [e for e in data if e%p != 0]

def is_prime(n):
    if n == 1:
        return False
    for i in range(2,n):
        if i * i > n:
            break
        if n%i == 0:
            return  False
    return True

def main():
    n = int(input())
    if n == 1:
        print(0)
        return

    primes = sieve(n)
    ans = 1
    for p in primes:
        if p == 2:
            continue
        if p * p - 2 <= n and is_prime(p * p - 2):
            #print(p * p - 2,2,p)
            ans += 2

    print(ans)

if __name__ =='__main__':
    main()