use proconio::input;

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

    let mut is_stand = vec![false; n + 1];
    for i in 1..=n {
        for j in 1.. {
            if i * j > n {
                break;
            }
            is_stand[i * j] = !is_stand[i * j];
        }
    }

    println!("{}", is_stand[1..].iter().filter(|x| **x).count());
}