<?php
$x = trim(fgets(STDIN));
$y = trim(fgets(STDIN));
$maxLength = trim(fgets(STDIN));
$count = 0;

if ($x != 0) {
    if($y >= 0){
        $count++;
    }else{
        $count +=2;
    }
}

$absX=abs($x);
$absY=abs($y);

$countX=$absX/$maxLength;
if($absX%$maxLength != 0){
    $countX++;
}

$countY=$absY/$maxLength;

if($absY%$maxLength != 0){
    $countY++;
}

$count = $count + (int)$countX + (int)$countY;

echo $count;