sub leonardo{
    my $n = shift;
    if($n == 0 || $n == 1){
        return 1;
    }
    else{
        return leonardo($n-2)+leonardo($n-1)+1;
    }
}
##</code><code>##

sub leonardo {
    my $n = shift;
    $n == 0 || $n == 1 and
        return 1;
    return leonardo ($n - 2) + leonardo ($n - 1) + 1;
    }

##</code><code>##

sub leonardo {
    my $n = shift;
    $n == 0 || $n == 1 ? 1 : leonardo ($n - 2) + leonardo ($n - 1) + 1;
    }