#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

vector<int> Sieve(int n){
    vector<int> lst(n + 1, 1);
    for (int i = 2; i <= n; i++){
        if (lst[i]){
            for (int j = 2 * i; j <= n; j += i){
                lst[j] = 0;
            }
        }
    }
    return lst;
}

int main()
{
    int N;
    cin >> N;
    vector<ll> L(N + 1, 1);
    vector<int> lst;
    lst = Sieve(N);
    for (int i = 2; i <= N; i++){
        if (lst[i] == 0){
            continue;
        }
        ll now = i;
        int pm = 1;
        while (now <= N){
            for (int j = now; j <= N; j += now){
                if (pm == 1){
                    L[j] *= i;
                }
                else{
                    L[j] /= i;
                }
            }
            now *= i;
            pm *= -1;
        }
    }

    int n = 1;
    vector<int> A;
    while (n * n <= N){
        A.push_back(n * n);
        n++;
    }

    ll ans = 0;
    for (int i = 1; i <= N; i++){
        auto it = upper_bound(A.begin(), A.end(), N/L[i]);
        ans += distance(A.begin(), it);
    }
    cout << ans << endl;

}