A, B, C, and D are divided into 28 sheep. A, B, C, and D get (1/2), (1/5), (1/6), and (1/15) respectively. How should they be divided?
甲、乙、丙、丁分28头羊．甲、乙、丙、丁分别得(1/2)，(1/5)，(1/6)，(1/15)，应如何分？
<result>28</result>