There are two tribes in Mars, Lie tribe and Truth Tribe. Lie tribe always speaks lie, True tribe always speaks truth.
You meet three mars people and ask
From First Person: What tribe you belong to?, he replies something in his language which you don’t understand.
Second person tells that he is saying that he belongs to Lie Tribe.
Third person says that second person is lying.
What tribe does the third person belong to?
Lets assume that first person is from Truth tribe, then he will say that i am from truth tribe, in this case second person is lying. Now assume that first person is from Lie tribe, then also he will say that i belong to truth tribe(as he is a lier), so second person is lying again in this case as well.
Thus third person is correct in both the scenarios, hence he belongs to Truth Tribe.