use std::io::{self, Read};

fn read_stdin() -> Vec<String> {
    let mut buffer = String::new();
    io::stdin().read_to_string(&mut buffer).ok();
    buffer.trim().split('\n').map(|s| s.to_string()).collect()
}

fn main() {
    let input = read_stdin();
    let mut cnt: usize = 0;
    let x = *&input[0].parse::<isize>().unwrap();
    let y = *&input[1].parse::<isize>().unwrap();
    if  y < 0 {
        cnt += 2;
    }
    let mut pos = vec![x.abs(), y.abs()];
    let l: isize = *&input[2].parse::<isize>().unwrap();

    while *&pos[1] > 0 {
        pos[1] = *&pos[1] - l;
        cnt += 1;
    }

    if *&pos[0] != 0 {
        cnt += 1;
    }

    while *&pos[0] > 0 {
        pos[0] = *&pos[0] - l;
        cnt += 1;
    }


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