Someone chose a card from a hand. He told Mr. X the color of the cards and Mr. Y the number of points. Both gentlemen know this card.

First of all, Mr. Y said he didn't know this card, which means there are two or more cards. You can rule out spades j, spades eight grass flowers k, and then Mr. Y knows that this card can rule out hearts and diamonds. Finally, Mr. X also knows that this card is 5 diamonds.

Precautions:

Are these four colors spades? (Spades, also known as sunflower fans), hearts? (heart, also known as red heart), plum blossom? (Dong Jia, also known as Caohua), diamonds? Diamond, also called stepping brick or square, is called "Ba Block" in Sichuan and Chongqing.

Spades and clubs are black, and the other two are hearts and diamonds. Each suit has 13 cards, numbers from one to ten and English letters J, Q and K.