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

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

node *head=NULL;
node *tail;
node *newnode;

void create(int val){
    node * newnode=(node*)malloc(sizeof(node));
    newnode->data=val;
    newnode->next=NULL;
    
    if(head==NULL){
        head=newnode;
        tail=newnode;
    }
    else{
        tail->next=newnode;
        tail=newnode;
    }
}
void display(){
    node *tem=head;
    node *tem1=head;
    int count=0;
    int flag=0;
    while(tem ! =NULL){
     count++;
     if(!(count %2==0)){
         printf("%d",tem->data);
     }
     tem=tem->next;
    }
while(tem1!=NULL){
    flag++;
    if(flag%2==0){
        printf("%d",tem1->data);
    }
    
    temp1=tem1->next;
    
}
}
int main(){
    int n,val;
    scanf("%d",&n);
    for(int i=0;i<n;i++){
        if(!(scanf("%d",&val))){
            printf("Invalid input");
            return 0;
        }
        create(val);
    }
    if(n<0){
        printf("Invalid input");
        return 0;
    }
    display();
    return 0;
}