#include <stdio.h>
#include <stdlib.h>
typedef struct node{
    int data;
    struct node *left;
    struct node *right;
}a;
a *root = NULL;
a *create(int num){
    a * newNode=(a*)malloc(sizeof(a));
    newNode->data=NULL;
    newNode->left=NULL;
    newNode->right=NULL;
}
a* insert(a* root,int 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 n;
    char(num);
    scanf("%d",&n);
    if(n<0){
        printf("Invalid input");
        return 0;
    }
    for(int i=0;i<n;i++){
        scanf("%c",num);
        if(num == '\n'){
            continue;
        }
        root = insert(root,num);
    }
    inorder(root);
return 0;
    
}