Give the number of Moroccan customers whose account is in debt.
account is in debt if c_acctbal < 0; Moroccan customers refer to c_name WHERE n_name = 'MOROCCO';
SELECT COUNT(T1.c_name) FROM customer AS T1 INNER JOIN nation AS T2 ON T1.c_nationkey = T2.n_nationkey WHERE T2.n_name = 'MOROCCO' AND T1.c_acctbal < 0