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

Btree belong_Btree_rec(Btree B, int v)
{
	if (B)
	{
		if (B->data == v)
			return B;
		return (belong_Btree_rec(B->left, v) || belong_Btree_rec(B->right, v))?B:NULL;
	}
	return NULL;
}
	
int nb_common_entries(Btree B, Btree C)
{
    int nbl, nbr;
    if(B)
    {
        nbl = nb_common_entries(C, B->left);
        nbr = nb_common_entries(C, B->right);
        if(belong_Btree_rec(C, B->data))
            return 1 + nbl +nbr ; 
        else
            return nbl +nbr;
    }
}