Find the number of the products that have their color described as "red" and have a characteristic named "slow".
select count(*) from products as t1 join product_characteristics as t2 on t1.product_id = t2.product_id join characteristics as t3 on t2.characteristic_id = t3.characteristic_id join ref_colors as t4 on t1.color_code = t4.color_code where t4.color_description = "red" and t3.characteristic_name = "slow"