/**
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};
*/
class Solution {
public:
    int dpsserch(TreeNode* root){
        if(root == nullptr){
            return 0;
        }else{
            int ans = 0;
            ans = dpsserch(root->left)+dpsserch(root->right)+1;
            return ans;
        }
    }
    int nodeNum(struct TreeNode* head) {
        
        return dpsserch(head);
    }
};