fn get_primes(n: usize) -> Vec<bool> {
    let mut flgs = vec![true; n+1];
    flgs[0] = false;
    flgs[1] = false;

    for i in 2..=(n as f64).sqrt().ceil() as usize {
        if !flgs[i] { continue; }
        for j in i..=n/i {
            flgs[i*j] = false;
        }
    }

    flgs
}

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

    if n == 1 {
        println!("0");
        return;
    }
    let primes = get_primes(n);
    let mut result = 0usize;
    for q in 2..=n {
        if !primes[q] { continue; }
        let r = ((2 + q) as f64).sqrt().floor() as usize;
        if r * r == 2 + q && primes[r] {
            result += 1;
        }
    }
    if result == 0 {
        println!("0");
        return;
    } else {
        println!("{}", result * 2 - 1);
    }
}