my $X = <>;
my $Y = <>;
my $K = <>;

#to make a positive number
my $pX = sqrt($X*$X);
my $pY = sqrt($Y*$Y);

my $remainder = ($pX+$pY) % $K;
my $count = ($pX + $pY - $remainder)/$K;

if (0 == $X){
    print "$count\n";
}elsif (0 < $X){
    $count += 1;
    print "$count\n";
}else{
    $count += 2;
    print "$count\n";
}