/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */


/**
 * Note: The returned array must be malloced, assume caller calls free().
 */

int n, *arr;

void getElements(struct TreeNode *root){
    if(!root)
        return;
    getElements(root->left);
    getElements(root->right);
    arr[n++] = root->val;
}

int compare (const void * a, const void * b)
{
  return ( *(int*)a - *(int*)b );
}

int* getAllElements(struct TreeNode* root1, struct TreeNode* root2, int* returnSize){
    arr = malloc(10000 * sizeof(int));
    n = 0;
    getElements(root1);
    getElements(root2);
    qsort(arr, n, sizeof(int), compare);
    *returnSize = n;
    return arr;
}