Among the suppliers providing parts under the type "promo brushed steel", how many of them are in debt?
type "promo brushed steel" refers to p_type = 'PROMO BRUSHED STEEL'; in debt refers to s_acctbal < 0
SELECT COUNT(T3.s_name) FROM part AS T1 INNER JOIN partsupp AS T2 ON T1.p_partkey = T2.ps_partkey INNER JOIN supplier AS T3 ON T2.ps_suppkey = T3.s_suppkey WHERE T3.s_acctbal < 0 AND T1.p_type = 'PROMO BRUSHED STEEL'