输入5个学生成绩（从0到100的整数），并将这5个学生成绩保存至文件“data.txt”. 从文件“data.txt”中读取学生成绩，计算并输出平均值，然后按成绩的高低排序并输出。-Enter 5 pupils (an integer from 0 to 100), and the five student achievement save to a file " data.txt" . From the file " data.txt"　student achievement in reading, calculation and output, on average, then sorted by level of achievement and outputs.