count_no_of_nodes.cpp

using namespace std;

class node
{
    public:
	int data;
	node* left;
	node* right;
   node(int d)
   {
   	data =d;
   	left=NULL;
   	right=NULL;
   }
};
 node *buildTree()
{
	int d;
	cin>>d;
	if(d==-1)
	{
		return NULL;
	}
	node* root=new node(d);
	root->left=buildTree();
    root->right=buildTree();
    return root;
}
int count(node* root)
{
	if(root==NULL)
	{
		return 0;
	}
	return 1+count(root->left)+count(root->right);
}
int main()
{
	node* root=  buildTree();
cout<<count(root)<<endl;
return 0;
}