fn main() {
    let x: i32 = read::<i32>();
    let y: i32 = read::<i32>();
    let l: i32 = read();

    let mut count = 0;
    if y >= 0 && x != 0 {
        count += 1;
    }
    else if y < 0 {
        count += 2;
    }

    let x = x.abs();
    let y = y.abs();

    let div_ceil = |a: &i32, b: &i32| -> i32 {
        if a % b == 0 {
            a / b
        }
        else {
            a / b + 1
        }
    };

    count += div_ceil(&x, &l) + div_ceil(&y, &l);

    println!("{}", count);
}

fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}