use std::io::*;
use std::str::*;

fn read<T: FromStr>(sl: &mut StdinLock) -> Option<T> {
    let s = sl.by_ref().bytes().map(|c| c.unwrap() as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect::<String>();

    s.parse::<T>().ok()
}

fn run(sl: &mut StdinLock) {
    let x = read::<i32>(sl).unwrap();
    let y = read::<i32>(sl).unwrap();
    let l = read::<i32>(sl).unwrap();

    let mut count = 0;
    if y < 0 { count += 2; }
    count += (y.abs() + (l - 1)) / l;

    if x != 0 {
        if y >= 0 { count += 1; }
        count += (x.abs() + (l - 1)) / l;
    }

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

fn main() {
    let s = stdin();
    let mut sl = s.lock();
    run(&mut sl);
}