#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
struct Node{
    struct Node*createNode(int data){
        struct Node *newNode = (struct Node*)malloc(size of(struct Node));
        newNode->data = data;
        newNode->next = NULL;
        return newNode;
    }
int main(){
    int n,i,val;
    if (scanf("%d",&n)!=1|| n <= 0)
{
      printf("invalid input");
      return 0;
   }
   struct Node *head =NULL,*temp = NULL;
   for (i=0;i<n;i++){
       if(scanf("%d",&val)!=1|| val<0){
           printf("invalid input");
           return 0;
       }
       struct node *newnode = createNode(val);
       if(head==NULL){
           head=newnode;
           temp=newnode;
       }else{
           temp->next=newNode;
       }
   }
   temp=head;
   while(temp !=NULL){
       printf("%d",temp->data);
       if(temp->next !=NULL)
       printf("");
       temp=temp->next;
   }
   return 0;
}