use proconio::input;

fn main() {
    input! { n: usize }

    let mut mu = vec![1; n + 1];
    let mut sieve = vec![true; n + 1];
    for i in 2..=n {
        if sieve[i] {
            for j in (i..=n).step_by(i) {
                sieve[j] = false;
                mu[j] *= -1;
            }
            for j in (i * i..=n).step_by(i * i) {
                mu[j] = 0;
            }
        }
    }
    let ans = mu[1..].iter().sum::<i32>();
    println!("{ans}");
}