#include<stdio.h>
#include<stdlib.h>
typedef struct treenode{
    int data;
    struct treenode *right;
    struct treenode *left;
}node;
node *root = NULL;
node *newnode;
node *create(int num){
    node *newnode = (node*)malloc(sizeof(node));
    newnode->data=num;
    newnode->left=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
    root->right = insert(root->right, num);
    return root;
}
void level node(node *root){
    if(root==NULL){
        return;
    }
    node* queue[100];
    int front = 0, rear = 0;
    queue[rear++] = root;
    while(front<rear){
        node* curr = queue[front++];
        printf(cuur->left);
        if(curr->left){
            queue[rear++]=curr->left;
        }
        if(curr->right){
            queue[rear++]=curr->right;
        }
        }
    }
}
int main(){
    int num, size;
    scanf("%d", &size);
    if(size<0){
        printf("Invalid input");
        return 0;
    }
for(int i=0; i<size; i++){
    scanf("%d", &num);
    root = insert(root, num);
}
level(root);
return 0;
}