<?php
// Your code here!

    $x = trim(fgets(STDIN));
    $y = trim(fgets(STDIN));
    $a = trim(fgets(STDIN));
    
    $ct = 0;

    if ($x == 0 && $y ==0 ) {
        echo 0;
    } else if ($y == 0 && $x != 0) {
        $ct++;
        $ct += ceil(abs($x) / $a);
    } else if ($x == 0 && $y > 0) {
        $ct += ceil(abs($y) / $a);
    } else if ($x == 0 && $y < 0) {
        $ct += 2;
        $ct += ceil(abs($y) / $a);
    } else if ($y > 0) {
        $ct += ceil(abs($y) / $a);
        $ct++;
        $ct += ceil(abs($x) / $a);
    } else {
        $ct++;
        $ceil(abs($x) / $a);
        $ct++;
        $ceil(abs($x) / $a);
    }
    
    echo $ct;
    
?>