#include<stdio.h>
#include<stdlib.h>
typedef struct node
{
    int data;
    struct node*next;
    struct node*prev;
}Node;
Node*head=NULL,*tail;
void create(int num)
{
    Node *newNode=(Node*)malloc(1*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 n,i,num;
     scanf("%d",&n);
     if(n<0||n==0)
     {
         printf("Invalid input");
         return 0;
         
     }
     for(i=0;i<=n;i++)
     {
         if(scanf("%d",&num)!=0)
         {
             printf("Invalid input");
             return 0;
         }
         create(num);
     }
     display();
}