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;

my $count_r;

if($remainder != 0){
    $count_r = 1;
}else{
    $count_r = 0;
}

my $turn;

if($X == 0 && $Y > 0){
    $turn = 0;
}elsif($Y < 0){
    $turn = 2;
}else{
    $turn = 1;
}

my $ans = $count + $count_r + $turn;

print "$ans\n";