/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int treeDepth(TreeNode* root) {
        if(root==NULL)return 0;

        int l=treeDepth(root->left);
        int r=treeDepth(root->right);

        return max(l,r)+1;


    }
};