// editor4
#include<stdio.h>
#include<stdlib.h>

typedef struct Node{
    int data;
    struct Node *left, *right;
}Node;

Node *createNode(int data){
    Node *newNode=(Node*)malloc(sizeof(Node));
    newNode->data=data;
    newNode->left=newNode->right=NULL;
    return newNode;
}

Node* buildTree(int arr[], int n, int index) {
    if (index >= n || arr[index] == 0)
    return NULL;
    
    Node* root = createNode(arr[index]);
    root->left = buildTree(arr, n, 2 * index + 1);
    root->right = buildTree(arr, n, 2 * index + 2);
    return root;
}
void printNodes(Node* root) {
    if (root == NULL)return;
    
    if (root->left == NULL || root->left == -1 && root->right == NULL || root->right == -1 ) {
        printf("%d ", root->data);
        return;
    }
    printNodes(root->left);
    printNodes(root->right);
}

int main(){
    int n;
    scanf("%d", &n);
    if(n<=0){
        printf("Invalid input");
        return 0;
    }
    int arr[n];
    for (int i = 0; i < n; i++)
    scanf("%d", &arr[i]);
    
    Node* root = buildTree(arr, n, 0);
    
    printNodes(root);
    return 0;
}