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 number, and press the average points in descending order to output each player ranking, name, average score.