Pls answer question correctly. Previous chegg answer for this is incorrect.

Let L1,L2,L3, be countably many languages over possibly different alphabets, i.e., Lii where each i is some finite alphabet that may vary with i. Prove that L=L1L2L3 is countable. This should hold even if the "combined alphabet" =123 is infinite. 2 For example, we might have 1={0,1},2={0,1,2}, and i={0,1,2,,i} in general. Then the combined alphabet ={0,1,2,}=N is the infinite set of natural numbers, so L is a set of strings whose "characters" may be any natural numbers