Diao Yang has many balls with different colors. Today he wants to divide his balls into two groups. But he does not know how to divide. Then Diao Ze gives him a suggestion: first you choose a ball and put it into the first group. Then from the second ball, if the color of the ball is same to the last ball you has chosen, then you put the ball into the other group. Otherwise you put the ball into the same group with the last ball. Diao Yang thinks it is OK.
Then the problem is, Diao Yang wants to know the product of the number of two groups’ balls. Can you help him?