#!/usr/bin/perl

use strict;
use warnings;

my $x = <>;
my $y = <>;
my $l = <>;
my $ans = 0;

if($x  < 0) {
	$x *= -1;
	if($y > 0) {
		$ans++;
	}
}

if($y < 0) {
	$y *= -1;
	$ans += 2;
}
if($x % $l == 0) {
	$x = $x / $l;
} else {
	$x = $x / $l;
	$x = int $x;
	$x++;
}

if($y % $l == 0) {
	$y = $y / $l;
} else {
	$y = $y / $l;
	$y = int  $y;
	$y++;
}

#print "$x, $y, $ans\n";
$ans += $x + $y;

print "$ans\n";

exit;