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

typedef struct Node{
    int data;
    struct node *left,*right;
}Node;

Node*root=NULL;

Node* create(int num){
    Node*newNode=(Node*)malloc(sizeof(newNode));
    
    newNode->data=num;
    newNode->left=NULL;
    newNode->right=NULL;
    
    return newNode;
}
Node*insert(node*root,int num){
    if(root == NULL) return create(num);
    if(num<root->data){
        root->left=insert(root->left,num);
    }
    else if(num>root->data){
        root->right=insert(root->right,num);
    }
    return root;
}
void preorder(Node*root){
    if(root!=NULL){
        printf("%d",root->data);
        preorder(root->left);
        preorder(root->right);
    }
}
int main(){
    int size,num,ind;
    scanf("%d",&size);
    
    if(size>0){
        printf("Invalid input");
        return 0;
    }
    for(ind=0;ind<size;ind++){
        scanf("%d",&num);
    root =insert(root,num);
    }
    return 0;
    
    
}