<?php
$input_lines = trim(fgets(STDIN));
$input_lines = str_replace(array("\r\n","\r","\n"), "", $input_lines);
do {
    $tmpStr[] = $input_lines;
    $input_lines = trim(fgets(STDIN));
    $input_lines = str_replace(array("\r\n","\r","\n"), "", $input_lines);
} while ($input_lines !== "");

$x = $tmpStr[0];
$y = $tmpStr[1];
$move = $tmpStr[2];

$changeAngleCount = getChangeAngleCount((int)$x,(int)$y);
$moveCount = ceil(abs($x) / $move) + ceil(abs($y) / $move);

echo $changeAngleCount + $moveCount;

function getChangeAngleCount($i_x,$i_y){
	if($i_y >= 0){
		if($i_x === 0){
			return 0;
		}else{
			return 1;
		}
	}else{
		return 2;
	}
}