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

int main() {
	int N;
	cin >> N;
	
	vector<int> lp(N + 1, -1);
	for(int i = 2; i <= N; ++i) if(lp[i] == -1) for(int j = i; j <= N; j += i) lp[j] = i;
	
	vector<int> mu(N + 1, 1);
	for(int i = 2; i <= N; ++i) {
		if(i / lp[i] % lp[i] == 0) mu[i] = 0;
		else mu[i] = mu[i / lp[i]] * -1;
	}
	
	int ans = 0;
	for(int i = 1; i <= N; ++i) ans += mu[i];
	
	cout << ans << "\n";
}