求一段循环语句的C语言程序

#include
void main()
{
int a;
scanf("%d",&a);
switch(a)
{
case 10:
case 9: printf("(90~100)\n");break;
case 8:printf("(80~89)\n");break;
case 7:printf("(70~79)\n");break;
case 6:printf("(60~69)\n");break;
case 5:
case 4:
case 3:
case 2:
case 1:
case 0:printf("(0~59)\n");break;
default: printf("ERROR\n");break;
}
}