#include <bits/stdc++.h>

using namespace std;
const int N = 1010;
int a[N];
int n, cnt;

int main() {
    cin >> n;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= 2 * n; j++)
            if (j % i == 0)a[j] = !a[j];

    for (int i = 1; i <= 2 * n; ++i)
        if (a[i]) cnt++;
    printf("%d", cnt);
    return 0;
}