Among the customers from Morocco, how many customers were in debt?
customers refer to c_custkey; Morocco is the name of the nation which refers to n_name = 'MOROCCO'; in debt refers to c_acctbal < 0;
SELECT COUNT(T1.c_custkey) FROM customer AS T1 INNER JOIN nation AS T2 ON T1.c_nationkey = T2.n_nationkey WHERE T1.c_acctbal < 0 AND T2.n_name = 'MOROCCO'