#include<stdio.h>
#include<stdlib.h>
typedef struct node{
  int data;
  struct node *left;
  struct node *right;
}Node;
Node *root=NULL;
Node *create(int num){
    Node *newnode=(Node*)malloc(1*sizeof(Node));
    newnode->data=num;
    newnode->left=NULL;
    newnode->right=NULL;
    return newnode;
}
Node *insert(Node *root,int num){
    if(root==NULL)
    return root(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 postorder(Node* root){
    if(root!=NULL){
    postorder(root->left);
    postorder(root->right);
    printf("%d",root->data);
    }
}
int main(){
    int n,i,num;
    scanf("%d",&n);
    if(n<0){
        printf("Invalid input");
        return 0;
    }
    for(i=1;i<=n;i++){
        scanf("%d",&num);
        root=insert(root,num);
        return 0;
    }
    postorder(root);
    return 0;
}