my $data = <STDIN>;
my (@data) = split (" ", $data);

my $n = shift (@data);
my $m = shift (@data);
my $a = shift (@data);

my $ma = $m/$a;
my $na = $n/$a;

if (int($ma) != $ma) {
    $ma = int($ma) +1;          
}

if (int($na) != $na) {
    $na = int($na) +1; 
}

$x = int($ma*$na);
print $x;