/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:

    vector<int> ans;

    void DFS(TreeNode* root){

        if(root==nullptr){
            return;
        }

        ans.push_back(root->val);

        DFS(root->left);
        DFS(root->right);

        return;

    }

    vector<int> getAllElements(TreeNode* root1, TreeNode* root2) {

        DFS(root1);
        DFS(root2);

        sort(ans.begin(),ans.end());

        return ans;

    }
};