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($remainder != 0){
    $count += 1;
}

my $turn;

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

$count += $turn;

print "$count\n";