How do you find out the coordination number of a crystal?

Question

For example im given a picture of the crystal structure of lithium sulfide Li2S.

SO i need to find coordination number for:

Li^+
S^2-

Answer 1

lithium i got right is 4 but the sulfide it says when counting sulfide: keeping in mind that another unit cell will be present above this one, so 4 for sulfide is wrong

Answer 2

lolz, you must a chma11 student at utsc. you are doing a great job for other 799 kids taking this course. keep it up. lol me stuck on the same question.