Hi, Good Morning and Welcome to the Forum!!!
If you're interested, you can use Contax C/Y (MM version) lenses on Pentax bodies by using Leitax remounting kits. There is a story behind this. In the late 70's, early 80's Zeiss and Pentax were cooperating (well after Ashai purchased the Pentax name from Zeiss). They co-developed a number of lenses. Anyway, the partnership dissolved for whatever reason and Zeiss went to Yashica to build the Contax. The K mount and the C/Y mount are nearly exactly the same - with the C/Y mount being ever so slightly shorter and with the mount flanges being thicker - by just enough that you are unable to use the C/Y mount on the Pentax bodies. Also, rumor has it that Zeiss licensed the SMC coatings for their T* coatings.
However, with the Leitax.com ---
Zeiss Contax lens for Pentax cameras you have a native K mount on the Contax glass and they shoot perfectly.
I have the Contax 28/f2.8 and the 85/f2.8 along with a number of Taks, K's, M's, A's and FA's with a few of the more recent lenses.