// editor2
#include<stdio.h>
#include<stdlib.h>
typedef struct node{ 
int data;
struct node *left;
struct node *right;
}node;
node *root =NULL;
node *create(int  val){
    node *newnode=(node*)malloc(sizeof(node));
    newnode->data = val;
    newnode->left = newnode->right=NULL;
    return newnode;
}
node *insertbst(node *root,int t){
    if(root == NULL)
    return create(t);
    if(t<root->data){
        root->left = insertbst(root ->left,t);
    }
    else
        root->right=insertbst(root->right,t);
        return root;
    
}
void postorder(node *root){
 if(root == NULL)
 return ;
postorder(root->left);
postorder(root->right);
printf("%d",root->data);
}
int main(){
    int size;
    scanf("%d ",&size);
    if(size<0){
        printf("Invalid input");
        return 0;
    }
    node *root=NULL;
    for(int i = 0;i<size;i++){
        int time;
        scanf("%d",&time);
        if(time<5){
            printf("Invalid input");
            return 0;
        }
        root = insertbst(root,time);
    }
    posorder(root);
}