#include <bits/stdc++.h>
using namespace std;

int main() {
	int N;
	cin >> N;
	
	vector<int> ps;
	ps.reserve(670000);
	vector<bool> comp(N + 1, 0);
	vector<int> mu(N + 1, 1);
	
	for(int i = 2; i <= N; ++i) {
		if(!comp[i]) {
			ps.push_back(i);
			mu[i] = -1;
		}
		
		for(auto p : ps) {
			if(i * p > N) break;
			comp[i * p] = 1;
			
			if(i % p == 0) {
				mu[i * p] = 0;
				break;
			}
			mu[i * p] = -mu[i];
		}
	}
	
	int ans = 0;
	for(int i = 1; i <= N; ++i) ans += mu[i];
	
	cout << ans << "\n";
}