use std::io;
use std::str::FromStr;

fn main() {
    let stdin = io::stdin();
    let mut buf = String::new();
    stdin.read_line(&mut buf).ok();

    let mut it = buf.split_whitespace().map(|n| i64::from_str(n).unwrap());
    let a = it.next().unwrap();

    let mut buf = String::new();
    stdin.read_line(&mut buf).ok();

    let mut it = buf.split_whitespace().map(|n| i64::from_str(n).unwrap());
    let b = it.next().unwrap();

    let mut buf = String::new();
    stdin.read_line(&mut buf).ok();

    let mut it = buf.split_whitespace().map(|n| i64::from_str(n).unwrap());
    let c = it.next().unwrap();

    let mut ans = 0;

    ans += (a / c).abs();
    ans += (b / c).abs();

    if a % c != 0 {
        ans += 1;
    }
    if b % c != 0 {
        ans += 1;
    }

    if a != 0 && b != 0 {
        ans += 1;
    }
    println!("{}", ans);
}