fn getline() -> String{
    let mut ret = String::new();
    std::io::stdin().read_line(&mut ret).ok();
    return ret;
}

fn main() {
    let x: f32 = getline().trim().parse().unwrap();
    let y: f32 = getline().trim().parse().unwrap();
    let l: f32 = getline().trim().parse().unwrap();
    let w: i32 = ((y.abs()/l).ceil() +
        if x.abs() > 0.0 {
            (x.abs()/l).ceil() + 1.0
        } else {
            0.0
        }) as i32;
    println!("{}", w)
}