输出最后为什么一直是-1？

#include<stdio.h>
#include<stdlib.h>
typedef int ElemType;
struct sNode
{
    ElemType data;
    struct sNode* next;
};
main()
{
    struct sNode x,y,z;
    struct sNode *p=&x;
    printf("x,y,z=");
    scanf("%d %d %d",&x.data,&y.data,&y.data);
    x.next=&y;
    y.next=&z;
    z.next=NULL;
    while(p!=NULL)
    {
        printf("%5d",p->data);
        p=p->next;
    }
    printf("\n");
    return 0;
}