Pentax K1000 - first lens advice

Newbie here.I recently picked up an original Pentax K1000 through an auction site for a ridiculously low price.As you can imagine, the camera came with a number of small issues, most of which aesthetic, and one huge problem: the inside of the lens is very moldy.I've never bought a lens for a camera, so I really don't know what I should be looking for.To give you an idea of my shooting habits, I mostly shoot landscapes when I go hiking plus the occasional portrait for a friend.Thank you.P. S.: I was Not sure if I should post it here or in the official questions thread as it's a bit too long for a post title; I'll move it if necessary. via /r/photography https://ift.tt/2IyZbdk