Somewhere there are two strange villages  Yang Zhuang's people lie on Monday, Wednesday and Friday  The Wangzhuang people lie on Tuesdays, Thursdays and Saturdays  On other days people in both villages tell the truth  One day, Liu, a foreigner who had never been here, met two people and asked them about the date
Both said, The day before yesterday was the day I lied
The day is Monday or Wednesday.