统计歌手大赛参赛人数，每名选手的平均得分。要求一次输入选手的编号、姓名、各评委的打分；输出参赛总人数，并按平均分由高到低的顺序输出每位选手的名次、姓名、平均得分。-Number of statistics singer contest entries, each players average score. Time to enter the players number, name, and all the judges scoring output the entry total numb