Maria and Martina are strange women. One of them always lies on Mondays, Tuesdays, and Wednesdays and tells the truth on all other days of the week while the other lies on Thursdays, Fridays, and Saturdays and tells the truth on other days of the week.

Today, following statements were made.
Maria: I lie on Saturdays.
Martina: I will lie tomorrow.
Maria: I lie on Sundays.

Which day of the week is today?

Wednesday.

No one lies on Sunday, so Maria is lying. Which means today is not Sunday. Also now we know that Maria lies today, so "Maria: I lie on Saturdays" is also a lie. Therefore, today is not sturdy and can one of Monday, Tuesday, or Wednesday. Now we know Martina is telling the truth, therefore for the statement "Martina: I will lie tomorrow." true today has to be Wednesday.

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