Some cards from an ordinary pack of playing cards were laid out on a table with face upwards. I thought of one card there, The KING OF HEARTS. I announced that I would tell Mr. A the value and Mr. B the suit of my chosen card. I whispered to Mr. A that I had chosen a KING and whispered to Mr. B that I had chosen a HEART. Their subsequent discussion went as below:
A: “I do not know the card that was chosen”
B: “I knew you would not”
A: “I still do not know the card, but at least I can now work out its colour”
B: “Now at last I can work out what card it is”
A: “So can I”
What is the least number of cards which could be on the table?
How many of those would be Diamonds?