#include<stdio.h>
#include<stdlib.h>
typedef struct node{
    int data;
    struct node *next;
    struct noden *prev;
}Node;
Node *head=NULL,*tail;
void create(int num){
    Node *newnode=(Node*)malloc(sizeof(Node));
    newnode->data=num;
    newnode->next=NULL;
    newnode->prev=NULL;
    if(head==NULL){
        head=newnode;
        tail=newnode;
    }
    else{
        newnode->prev=tail;
        tail->next=newnode;
        tail=newnode;
    }
}
void display(){
    Node *itr;
    for(itr=head;itr!=NULL;itr=itr->next){
        printf("%d ",itr->data);
    }
}
int main(){
    int size,num,itr;
    scanf("%d ",&size);
    if(size<=0){
        printf("Invalid input");
        return 0;
    }
    create(num);
  }
  display();
  return 0;
}