use std::io;

fn main() {
    let x = input_num();
    let y = input_num();
    let len = input_num();

    let mut count = 0;

    if x == 0 && y >= 0 {
        count = get_count(len, y);
    } else if x != 0 && y >= 0 {
        count = get_count(len, y) + 1 + get_count(len, x);
    } else if y < 0 {
        count = get_count(len, x) + 2 + get_count(len, y);
    }

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

fn get_count(len: i64, dist: i64) -> i64 {
    if dist.abs() % len == 0 {
        dist.abs() / len
    } else {
        dist.abs() / len + 1
    }
}

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