fn get_factors(n: usize) -> Vec<usize> {
    let mut flgs = vec![true; n+1];
    flgs[0] = false;
    flgs[1] = false;
    let mut ret = (0..=n).collect::<Vec<_>>();

    for i in 2..=n {
        if !flgs[i] { continue; }
        let base = i * i;
        for j in i..=n/i {
            let idx = i*j;
            flgs[idx] = false;
            while ret[idx] % base == 0 {
                ret[idx] /= base;
            }
        }
    }

    ret
}

fn main() {
    let mut n = String::new();
    std::io::stdin().read_line(&mut n).ok();
    let n: usize = n.trim().parse().unwrap();

    let factors = get_factors(n);
    let mut cnts = vec![0usize; n+1];
    for &v in factors.iter() {
        cnts[v] += 1;
    }
    let mut result = 0usize;
    for a in 1..=n {
        result += cnts[factors[a]];
    }
    println!("{}", result);
}