Riddle Stalin "which finger the middle?

Then clenched his fist and put three fingers - thumb, index and middle. "Which of these three fingers average?" - Asked Stalin.
Churchill was surprised simplicity puzzles and grabbed the index finger "That's the average!»
"No, do not guess," - said Stalin.
Roosevelt felt that Stalin was cunning, and you should choose them all and 5-fingers. Therefore, he pointed to the middle finger.
"No, you did not guess," - said Stalin. Then folded his fist three fingers of his left hand and showed it to Churchill and Roosevelt: "Here the average! Here you have our Crimea! »