#include <stdio.h>
#define NULL 0
struct student
{
    char name[20];
    char sex;
    int num, year;
    struct student *next;
};
struct student *input(struct student *head)
{
    int n = 0;
    struct student *p1, *p2;
    p1 = p2 = (struct student*) malloc (sizeof(struct student));
    printf ("please enter information:");
    scanf ("%s%d%c%d", p1->name, &p1->num, &p1->sex, &p1->year);
    while (p1->num > 0)
    {
        n++;
        if (n == 1)
        {
            head = p1;
        }
        else
        {
            p2->next = p1;
            p2 = p1;
        }
        p1 = (struct student*) malloc (sizeof(struct student));
        scanf ("%s%d%c%d", p1->name, &p1->num, &p1->sex, &p1->year);
    }
    p2->next = NULL;
    return (head);
}
void output (struct student *head)
{
    struct student *p;
    p = head;
    while (p != NULL)
    {
        printf ("%s     %d     %c     %d", p->name, p->num, p->sex, p->year);
        p = p->next;
    }
}
void main ()
{
    struct student *head;
    head = NULL;
    head = input (head);
    output (head);
}