from collections import *
from itertools import *
from functools import *
from heapq import *
import sys,math
input = sys.stdin.readline


class prime_factorize():
    
    def __init__(self,M=10**6):
        self.sieve = [-1]*(M+1)
        self.sieve[1] = 1
        self.p = [False]*(M+1)
        self.mu = [1]*(M+1)
        
        for i in range(2,M+1):
            if self.sieve[i] == -1:
                self.p[i] = True
                
                i2 = i**2
                for j in range(i2,M+1,i2):
                    
                    self.mu[j] = 0
                
                
                for j in range(i,M+1,i):
                    self.sieve[j] = i
                    
                    self.mu[j] *= -1
                    
    def factors(self,x):
        tmp = []
        while self.sieve[x] != x:
            tmp.append(self.sieve[x])
            x //= self.sieve[x]
        tmp.append(self.sieve[x])
        return tmp
        
    def is_prime(self,x):
        return self.p[x]
        
    def mobius(self,x):
        return self.mu[x]

N = int(input())
pf = prime_factorize()
ans = 0
S = set()
P = set()
for i in range(2,N+1):
    if pf.is_prime(i):
        P.add(i)
        S.add(i**2)

if N==1:
    print(0)
    exit()
p = 2
for q in P:
    if (q+2) in S:
        ans += 1
print(ans*2 - 1)