How to map N keywords based on delimiter

Question

I have N keywords which can be mapped as follows:

1,2,3,4----/5,6,7,8----/9,10,11,12----/--------

From the above line i should be able to map 1 to 5,2 to 6, 3 to 7, so on. I should also be able to map 1 to 9, 1 to 10, 1 to 11, 1 to 12 so on like that i should be able to map N number of combinations. I should make this generic in such a way that it should work with N number of combinations. Please tell me the logic how i can do this.

Thanks & Regards,
P.Karthik