题目：有五个学生，每个学生有3门课的成绩，从键盘输入以上数据（包括学生号，姓名，三门课成绩），计算出平均成绩，况原有的数据和计算出的平均分数存放在磁盘文件"stud"中。-Title: five students, each student a 3-course results, the above data entered from the keyboard (including student number, name, three-course results), calculate the average score of the status of the original data and the calculated averageThe fraction is stored in the disk file "stud".