void main()
{
int n;
printf("请输入学生成绩");
scanf("%d",&n);
swutch(n/10)
{
case 10:
case 9:
printf("A\n");
break;
case 8:
printf("B\n");
break;
case 7:
case 6:
printf("C\n");
break;
case 5:
case 4:
case 3:
case 2:
case 1:
printf("D\n");
break;
default:
printf("输入错误");
}
}