Four people, A, B, C, and D, participate in a mathematics competition. The scores of the four are different but all are integers. The average score of the four is 80 points. What is the minimum.
甲乙丙丁四人参加数学比赛，四人分数各不相同但都是整数，四人的平均分是80分，甲得分最少，比乙少5分，丁得分最多，比丙多9分，丁得分最少是多少．
<result>89</result>