#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
// using namespace atcoder;
// using mint = modint1000000007;
// const int mod = 1000000007;
// using mint = modint998244353;
// const int mod = 998244353;
// const int INF = 1e9;
// const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i, l, r) for (int i = (l); i < (r); ++i)
#define rrep(i, n) for (int i = (n)-1; i >= 0; --i)
#define rrep2(i, l, r) for (int i = (r)-1; i >= (l); --i)
#define all(x) (x).begin(), (x).end()
#define allR(x) (x).rbegin(), (x).rend()
#define P pair<int, int>
template<typename A, typename B> inline bool chmax(A& a, const B& b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A& a, const B& b) { if (a > b) { a = b; return true; } return false; }
#ifndef KWM_T_MATH_SIEVE_HPP
#define KWM_T_MATH_SIEVE_HPP

#include <vector>

namespace kwm_t::math {

/**
 * @brief エラトステネスの篩（bool版）
 * is_prime[i] を返す
 */
inline std::vector<bool> sieve(int n) {
	std::vector<bool> is_prime(n + 1, true);

	if (n >= 0) is_prime[0] = false;
	if (n >= 1) is_prime[1] = false;

	for (int p = 2; p * p <= n; ++p) {
		if (!is_prime[p]) continue;
		for (int i = p * p; i <= n; i += p) {
			is_prime[i] = false;
		}
	}
	return is_prime;
}

/**
 * @brief 素数列挙
 * sieve を利用して primes を返す
 */
inline std::vector<int> primes(int n) {
	auto is_prime = sieve(n);
	std::vector<int> res;

	for (int i = 2; i <= n; ++i) {
		if (is_prime[i]) res.push_back(i);
	}
	return res;
}
}

#endif
int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);
	long long n; cin >> n;
	auto ps = kwm_t::math::primes(n);
	vector<int>g(n + 1, 1);
	for (auto p : ps) {
		for (int i = p; i <= n; i += p) {
			g[i] *= -1;
		}
		for (long long i = (long long)p * p; i <= n; i += (long long)p * p) {
			g[i] *= 0;
		}
	}
	int ans = 0;
	rep2(i, 1, n + 1)ans += g[i];
	cout << ans << endl;
	return 0;
}