In a game of Go, every two players have to play one game, the winner gets 2 points, each player gets 1 point for the tie, and the loser gets 0 points. Now five students have counted the total scores of all the players, which are 505, 506, 507, 508, and 509, but only one of the statistics is correct, so how many players participated in the competition?
在一次围棋比赛中，每两个人都要赛一场，胜者得2分，平局每人各得1分，负者得0分．现有五位同学统计了全部选手的总分，分别是505、506、507、508、509，但只有一个统计是正确的，则共有多少选手参赛．
<result>23</result>