Among the customers in Asia, how many customers are in debt?
customers in Asia refer to n_name where r_name = 'ASIA'; customers in debt refer to c_acctbal < 0;
SELECT COUNT(T1.n_name) FROM nation AS T1 INNER JOIN customer AS T2 ON T1.n_nationkey = T2.c_nationkey INNER JOIN region AS T3 ON T1.n_regionkey = T3.r_regionkey WHERE T2.c_acctbal < 0 AND T3.r_name = 'ASIA'