Find if it is:

a) a regular language;

b) a context-free language;

c) a recursively enumerable language;

If the case (a) is true for the language Li , build a finite automaton A such that L(A) = Li .

If the case (b) is true for the language Li, build a PDA D and a formal grammar G such that L(D) = L(G) = Li .

If the case (c) is true for the language Li, build a TM T such that L(T) = Li .