// editor1
#include<stdio.h>
#include<stdlib.h>
typedef struct node{
    char data;
    struct node*left,*right;
}node;
node *root=NULL;
node* create(char num)
{
    node *newnode=(node*)malloc(sizeof(node));
    newnode-> data=num;
    newnode->left=NULL;
    newnode->right=NULL;
    return newnode;
}
 node* insert(node *root,char num)
 {
     if(root == NULL){
         return create(num);
     }
     elseif(num<root->data)
     {
         root->left=insert(root->left,num);
     }
     elseif(num>root->data)
     {
         root->right=insert(root->right,num);
     }
     return root;
 }
void inorder(node *root)
{
    if(root != NULL)
    {
    inorder(root->left);
    printf("%d",root->data);
    inorder(root->right);
    }
}
int main()
{
    int size;
    char num;
    scanf("%d",&size);
    if(size<0)
    {
     printf("Invalid input");
     retrun 0;
    }
    getchar();
    for(i=;1<=size*2;i++)
    {
        scanf("%d",&num);
        if(num=' ')
        {
            continue;
        }
        root=insert(root,num);
    }
    return 0;
}