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

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

Node *root = NULL;
Node* create(char num){
    Node *newNode = (Node*)malloc(1*sizeof(Node));
    newNode->data = num;
    newNode->left = NULL;
    newNode->right = NULL;
    return newNode;
}

Node* insert(Node *root, char 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("%c ",root->data);
        preOrder(root->left);
        preOrder(root->right);
    }
}

int main(){
    int size,i;
    char num;
    scanf("%d",&size);
    for(i=0;i<size;i++){
        scanf("%c ",num);
        root = insert(root,num);
    }
    preOrder(root);
    return 0;
}