// 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,size,2*i+1);
    root->right = buildtree(arr,size,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("Inalid 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");
}