Poor Johnny is so busy this term. His tutor threw lots of hard problems to him and demanded him to
accomplish those problems in a month. What a wicked tutor! After cursing his tutor thousands of times,
Johnny realized that he must start his work immediately.
The very problem Johnny should solve firstly is about a strange machine called Warmouth. In the Warmouth
there are many pairs of balls. Each pair consists of a red ball and a blue ball and each ball is assigned a value.
We can represent a pair in the form of (R, B) in which R is the value of the red ball and B is of the blue one.
Warmouth has a generator to calculate the match value of two pairs. The match value of (R1, B1) and (R2,
B2) is R1*B2+R2*B1. Initially, Warmouth is empty. Pairs are sent into Warmouth in order. Once a new pair
comes, it will be taken into the generator with all the pairs already in Warmouth.
Johnny’s work is to tell his tutor the sum of all match values given the list of pairs in order. As the best
friend of Johnny, would you like to help him?