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