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

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int N; cin >> N;
    int Need = N;
    vector<bool> prime(Need+1,true);
    prime.at(0) = false; prime.at(1) = false;
    for(int i=2; i*i<=Need; i++){
        if(!prime.at(i)) continue;
        for(int k=i*i; k<=Need; k+=i) prime.at(k) = false;
    }
    vector<int> V(N+1,1);
    V.at(0) = 0;
    for(long long p=2; p<=N; p++) if(prime.at(p)){
        for(long long i=p; i<=N; i+=p) V.at(i) = -V.at(i);
        long long p2 = p*p;
        for(long long i=p2; i<=N; i+=p2) V.at(i) = 0;
    }

    cout << accumulate(V.begin(),V.end(),0) << endl;
}