#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*)maloc(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 inorder(node*root){
    if(root!=NULL){
        inorder(root->left);
        printf("%d ",root->data);
        inorder(root->right);
    }
}
int main(){
    int size,i;
    char num;
    scanf("%d",&size);
    if(size<0){
        printf("Invalid input");
        return 0;
    }
    for(i=0;i<=size,i++){
        scanf("%c",&num);
        root=insert(root,num);
    }
    inorder(root);
    return 0;
}