// editor1
#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->head=num;
    newnode->next=NULL;
    if(head==NULL){
        head=newnode;
        tail=newnode;
    }
    

else{
    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;
    scanf("%d",&size);
    if(size<=0){
        printf("Invalid input");
        return 0;
    }
    for(int itr=1;itr<=size;itr++){
        if(scanf("%d",&num)!=1{
            printf("Invalid input");
            return 0;
        }
        if(num< -1000 || num> -1000){
            printf("Invalid input");
            return 0;
        }
        create(num);
    }
    display();
    return 0;
}