use proconio::input;

fn main() {
	input! {
		x: f64,
		y: f64,
		l: f64,
	}

    let ans = if x == 0.0 && y >= 0.0 {
        (y / l).ceil() as isize
    } else if x.abs() > 0.0 && y >= 0.0 {
        ((y / l).ceil() + 1.0 + (x.abs() / l).ceil()) as isize
    } else {
        (1.0 + (x.abs() / l).ceil() + 1.0 + (y.abs() / l).ceil()) as isize
    };

	println!("{ans}");
}