use std::io::Read;

fn main() {
    let mut buf = String::new();
    std::io::stdin().read_to_string(&mut buf).unwrap();
    
    let mut iter = buf.split_whitespace();
    
    let x: isize = iter.next().unwrap().parse().unwrap();
    let y: isize = iter.next().unwrap().parse().unwrap();
    let l: isize = iter.next().unwrap().parse().unwrap();
    
    let n_rotate = if y < 0 {
        2
    } else if x != 0 {
        1
    } else {
        0
    };
    
    let n_move = (x.abs() - 1) / l + (y.abs() - 1) / l + 2;
    
    println!("{}", n_rotate + n_move);
}