成绩转换

#include<stdio.h>
void fun(int x )
{
 int i;
 i=x/10;
 switch(i)
 {
  case 10:printf(x>100?"Score is error!\n":"A\n");break;
  case 9: puts("A");break;
  case 8: puts("B");break;
  case 7: puts("C");break;
  case 6: puts("D");break;
  case 5:
  case 4:
  case 3:
  case 2:
  case 1:
  case 0:printf(x<0?"Score is error!\n":"E\n");;break;
  default :printf("Score is error!\n");break;
}
}
int main( )
{
  int N;
  while(scanf("%d",&N)!=EOF)
    fun(N);
  return 0;
}
刚开始提交时wrong answer悲剧啊。。立哥告诉我，-9/10后为0…原来是错在这。。。。。