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

using ll = long long;

int main()
{
    int N;
    cin >> N;

    vector<bool> state(N, true);

    for (int i = 2; i <= N; i++)
    {
        for (int j = i; j <= N; j += i)
        {
            state[j - 1] = !state[j - 1];
        }
    }

    int ans = 0;
    for (int i = 0; i < N; i++)
    {
        ans += state[i];
    }

    cout << ans << endl;
}