#include <iostream>
using namespace std;

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:
    bool checkSymmetric(TreeNode* root1, TreeNode* root2) {
        if(!root1 && !root2) return true;
        if(!root1 || !root2) return false;
        if(root1->val != root2->val) return false;
        return checkSymmetric(root1->left, root2->right) && checkSymmetric(root1->right, root2->left);
    }
    bool isSymmetric(TreeNode* root) {
        return checkSymmetric(root, root);
    }
};

int main() {

}