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

typedef struct node{
    char data;
    node *left;
    node *right;
}node;

node *root ==NULL;

node *create(int num) {
    node* newnode=(node*)malloc(1*size of(node));
    newnode->data=NULL;
    newnode->left=NULL;
    newnode->right=NULL;
}
void inorder(node *root){
    if(root !=NULL){
        
    }
    node *newnode=(node*)malloc(1*sizeof(node));
    
    
}

int main(){
    int size,itr;
    char num;
    scanf("%d",&size);
    if(size<0) {
        printf("Invalid input");
        return 0;
    }
    getchar();
    for(itr=1;itr<=size*2;itr++) {
        scanf("%c",&num);
        if(num == ' ')
            continue;
        root = insert(root, num);
        getchar();
        root = insert(root,num);
    }
    inorder(root);
    return 0;
}