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