Write SQL query to solve given problem: Among the suppliers for the parts ordered in order no.4, how many of them are in debt?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT COUNT(T1.l_linenumber) FROM lineitem AS T1 INNER JOIN supplier AS T2 ON T1.l_suppkey = T2.s_suppkey WHERE T1.l_orderkey = 4 AND T2.s_acctbal < 0