#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);
    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");
        return 0;
    }