#include <iostream>
#include <cmath>
#include <vector>
using namespace std;

int main() {
    int n;
    cin >> n;
    freopen("even.in","r",stdin);
    freopen("even.out","w",stdout);
    vector<bool> is_prime(n+1, true);
    is_prime[0] = is_prime[1] = false;
    for (int i = 2; i <= n; i++) {
        if (is_prime[i]) {
            for (int j = i * i; j <= n; j += i) {
                is_prime[j] = false;
            }
        }
    }

    int ans = 0;
    for (int i = 1; i <= n; i++) {
        int cnt = 0, x = i;
        for (int j = 2; j <= n; j++) {
            if (is_prime[j]) {
                int p_cnt = 0;
                while (x % j == 0) {
                    x /= j;
                    p_cnt++;
                }
                cnt += p_cnt;
            }
        }
        if (cnt % 2 == 0) {
            ans++;
        }
    }
    cout << ans << endl;
    return 0;
}