#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(Node));
    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=create(root->left,num);
    else if(num >root->data)
       root->right=create(root->right ,num);
    return root;
}
void inOrder(Node *root,char num){
    if(root!=NULL){
        inOrder(root->left);
        printf("%c",root->data);
        inOrder(root->right);
    }
}
int main(){
    int size,itr;
    char num;
    scanf("%d",&size);
    if(size<0){
        printf("Invalid input");
        return 0;
    }
    getchar();
    for(itr=1;itr<=size;itr++){
        scanf("%d",&num);
        if(num==' ');
            continue;
        root=insert(root,num);
    }
    inOrder(root,num);
    return 0;
}