Gar the Magician wrote each of the numbers from 1 to 7, one on each of seven cards, and placed them in his hat. He offered the hat to two other magicians, Kan and Roo. Kan took, at random, 3 cards from the hat and Roo took 2 cards (so that there were 2 cards left in the hat). Kan told Roo: "I can deduce that the sum of the numbers of your cards is even". What was the sum of the numbers on Kan's cards?