<?php
$X = intval(fgets(STDIN));
$Y = intval(fgets(STDIN));
$L = intval(fgets(STDIN));

if ($X === 0) {
  if ($Y === 0) {
    echo "0\n";
  } else if ($Y > 0) {
    echo ceil($Y / $L) . "\n";
  } else {
    echo (ceil($Y / $L) + 2) . "\n";
  }
} else if ($Y === 0) {
  if ($X === 0) {
    echo "0\n";
  } else {
    echo (ceil($X / $L) + 1) . "\n";
  }
} else {
  $D = ceil(abs($X) / $L) + ceil(abs($Y) / $L);
  if ($X > 0 && $Y > 0) {
    $R = 1;
  } else if ($X > 0 && $Y < 0) {
    $R = 2;
  } else if ($X < 0 && $Y > 0) {
    $R = 1;
  } else if ($X < 0 && $Y < 0) {
    $R = 2;
  }
  echo ($D + $R) . "\n";
}