编写程序将一个百分制成绩转换为五分制成绩（switch形式）

#include<stdio.h>
main()
{
    int score,mark;
    printf("please enter score:");
    scanf("%d",&score);
    mark=score<0||score>100? -1:score/10;
    switch(mark)
    {
        case 10:
        case 9:printf("%d\tA\n",score);
               break;
        case 8:printf("%d\tB\n",score);
               break;
        case 7:printf("%d\tC\n",score);
               break;
        case 6:printf("%d\tD\n",score);
               break;
        case 5:
        case 4:
        case 3:
        case 2:
        case 1:
        case 0:printf("%d\tE\n",score);
               break;
        default:printf("Input error!\n");

    }
}