Write a function that returns the number of common entries in two BSTs.

	
BST belong_bst_rec(BST B, int v)
{
	if (B)
	{
		if (B->data == v)
			return B;
		if (B->data > v)
			return belong_bst_rec(B->left, v);
		else
			if (B->data < v)
				return belong_bst_rec(B->right, v);
	}
	return NULL;
}
	
	
int nb_common_entries(BST B, BST C)
{
    int nbl, nbr;
    if(B)
    {
        nbl = nb_common_entries(C, B->left);
        nbr = nb_common_entries(C, B->right);
        if(belong_bst_rec(C, B->data))
            return 1 + nbl +nbr ; 
        else
            return nbl +nbr;
    }
}