GTY is a GodBull who will get an Au in NOI . To have more time to learn algorithm knowledge, he never does his math homework. His math teacher is very unhappy for that, but she can’t do anything because GTY can always get a good mark in math exams. One day, the math teacher asked GTY to answer a question. There are four numbers on the blackboard – . Because GTY never does his homework, he can’t figure out this problem! If GTY can’t answer this question correctly, he will have to do his homework. So help him!
，但一定要背上几本书，在花海里，草丛旁悠然品味，
