What pen do you need for convertibles?

I bought an HP Pavilion x360, but it does not include a pen. But I do not want to spend too much, because the laptop itself was already expensive.

Which pen do you use or can you recommend?

After obviously a Edding 4000 was not so funny you can take that too:

according to the official list, the following should be compatible:

HP Pen (Microsoft)

1CP24AV / Y0C43AV

PLC: 920241-001 / 910942-001

But the pen of the Surface Pro 3/4 is also ok.

So about 20 euro.