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