#include<stdio.h>
#include<stdlib.h>

typedef struct node{
    int data;
    struct node *next;
}Node;

Node *head = NULL, *tail;

void create(int num){
    Node *newnode = (Node*)malloc (1*sizeof(Node));
    newnode->data =num;
    newnode->next = 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);
    }
}

void main(){
    int n,ind, num;
    scanf("%d",&n);
    if(n=0){
        printf("Invalid input");
        return 0;
    }
    for(ind=0; ind<n;ind++){
        scanf("%d",&n);
        
    }
}