这是学生成绩统计的另一部分，实现功能是有班级30个学生5门课，在主函数中输入、输出数据：

（1）函数average()求第一门课的平均分；

（2）函数findfail()找出有2门或2门以上课程不及格学生，输出其学号和全部课程成绩及平均成绩；

（3）函数findgood()找出平均成绩在90分以上或全部课程成绩在85分以上的学生。

-This is another part of student achievement statistics, to achieve functional class of 30 students is 5 course, the main function in the input and output data: (1) function average () find the first course of the average　(2) function findfail () to identify two or two or more courses failing students, student number and output a full course of its performance and the average score　(3) function findgood () to find out the average score of 90 points or more or all of the course grade in the 85 points or more students.