// editor1
#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 *buildTree(int arr[],int n,int i){
    if(i>=n || arr[i]==0){
    return NULL;
    }
    Node *root =create(arr[i]);
    root->left = buildTree(arr,n,2*i+1);
    root->right = buildTree(arr,n,2*i+2);
    return root;
}
void preorder(Node *root){
    if(root == NULL){
        return ;
    }
    printf("%d",root->data);
    preorder(root->left);
    preorder(root->right);
}
void inorder(Node *root){
    if(root == NULL){
        return;
    }
     inorder(root->left);
     printf("%d ",root->data);
    inorder(root->right);
    
    
    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;
        }
        int arr[size];
        for(int i = 0;i<size;i++){
            scanf("%d",&arr[i]);
        }
        Node *root = buildTree(arr,size,0);
        preorder(root);
        printf("\n");
        inorder(root);
        printf("\n");
        postorder(root);
        printf("\n");
    }