#include<stdio.h>
#include<stdlib.h>

typedef struct TreeNode {
    int data;
    struct TreeNode *left;
    struct TreeNode *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+1);
     return root;
}
void preorder(Node *root){
    if(root==NULL){
        return 0;
    }
    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 0;
    }
    postorder(root->left);
    postorder(root->right);
    printf("%d ",root->data);
}

int main(){
    int size;
    sacnf("%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;
}