Interrogation:
Are you a townsman? no
Are you Mafia? no
Are you Arhat? no
If the first is a lie, then he is a town member.
If the second is a lie, then he is Mafia, but not Arhat.
If the third is a lie, then it's a logical fallacy.
As you can see, the alibi is unreliable.
Если где-то чего-то убудет, то в другом месте добавится.
(Закон сохранения).