import math

# 0以上整数x「未満」の素数をリストに格納して返す
def primes(x):
    if x < 2: return []

    primes = [i for i in range(x)]
    primes[1] = 0 # 1は素数ではない

    # エラトステネスのふるい
    for prime in primes:
        if prime > math.sqrt(x): break
        if prime == 0: continue
        for non_prime in range(2 * prime, x, prime): primes[non_prime] = 0
    
    return [prime for prime in primes if prime != 0]

import sys
input = sys.stdin.readline
N = int(input())
dp = [0 for _ in range(N+1)]
dp2 = [0 for _ in range(N+1)]
P = primes(N+1)
for p in P:
    for i in range(p, N+1, p):
        dp[i] = 1-dp[i]
    for i in range(p*p, N+1, p*p):
        dp2[i] = 1
ans = 1
for i in range(2, N+1):
    if dp2[i]==1:
        continue
    if dp[i]==1:
        ans += -1
    else:
        ans += 1
print(ans)