#include<stdio.h>
#include<stdlib.h>
#define NULL 0
struct stu{
	int num,ch,ma,en;
	struct stu *next;
};
struct stu  *creat();
void main( )
{
	struct stu  *head,*p;
	float avc=0, avm=0, ave=0;
	int i=0;
	head= creat();  
	if(head == NULL)
		printf("沒有生成鏈表。\n");	           
    else{
		for (p=head; p; p= p->next){
	        avc+=p->ch ;
            avm+=p->ma ;
			ave+=p->en ;
			i++;
		}
		printf("語文、數學、英語的平均成績：\n");
		printf("%6.2f   %6.2f   %6.2f\n",avc/i,avm/i,ave/i);
	}
}
struct stu  *creat(){
	struct stu *head, *tail, *p;  
	int  ch,ma,en,num,i=1;  
	head = tail = NULL;
	printf("說明：結束時請輸入0 0 0 0。\n");
	printf("輸入第%d個學生的學號以及語文、數學、英語成績：\n",i);
   scanf("%d%d%d%d",&num,&ch,&ma,&en);
   while (num){
       p = (struct stu *)malloc(sizeof(struct stu));
	   p->num = num;    
	   p->ch = ch;  
	   p->ma = ma;
	   p->en = en;
	   p->next = NULL;
       if(head == NULL) head = p;
	   else  tail->next = p;
	   tail = p;
	   i++;
	   printf("輸入第%d個學生的學號以及語文、數學、英語成績：\n",i);
	   scanf("%d%d%d%d",&num,&ch,&ma,&en);
   }
   return head; 
}