fn read_num() -> i64 {
    use std::io::stdin;
    let mut s = String::new();
    let _ = stdin().read_line(&mut s);
    s.trim().parse().unwrap()
}

use std::cmp::Ordering::*;
pub fn main() {
    let (x, y, l) = (read_num(), read_num(), read_num());
    let rotate_inst = match (x.cmp(&0), y.cmp(&0)) {
        (Equal, Equal) => 0,
        (Equal, Greater) => 0,
        (_, Less) => 2,
        _ => 1,
    };
    let (ax, ay) = (x.abs(), y.abs());
    let move_inst = (ax + l - 1) / l + (ay + l - 1) / l;
    println!("{}", rotate_inst + move_inst);
}