Four people A, B, C, and D participate in a certain mathematics competition. The average score of A and B is a point. The score of C is 6 points higher than the average score of A and B. The score of D is higher than that of A and B. The average score of the two is 2 points lower. What is the average score of these four people?
甲、乙、丙、丁四人参加某次数学竞赛，甲、乙两人的平均成绩为a分，丙的成绩比甲、乙两人的平均成绩高6分，丁的成绩比甲、乙两人的平均成绩低2分．这四人的平均成绩为多少分．
<result>1</result>