#include<iostream>
#include<cstdlib>
using namespace std;
typedef struct DuLNode {
	int data;
	DuLNode *prior,*next;
};
void InitSList(DuLNode *&SL) {//初始化双链表 
	SL=(DuLNode*)malloc(sizeof(DuLNode));
	SL->prior=SL->next=NULL;
}
void createSList(DuLNode *&SL) {//创建双链表 
	DuLNode *s,*r;
	r=SL;
	while(1) {
		s=( DuLNode*)malloc(sizeof(DuLNode));  
		cin>>s->data;   
		if(s->data==-1)break;
		r->next=s;
		s->prior=r;
		r=s;
	}
	r->next=NULL;
}
void showSList(DuLNode *&SL) {  //输出双链表 
	DuLNode *p=SL->next;
	while(p) {
		cout<<p->data<<" ";
		p=p->next;
	}
	cout<<endl;
}
int main() {
	DuLNode *SL;
	InitSList(SL);
	createSList(SL);
	showSList(SL);
	return 0;
}