How many European suppliers are there?
European suppliers refer to s_suppkey where r_name = 'EUROPE';
SELECT COUNT(T1.n_nationkey) FROM nation AS T1 INNER JOIN region AS T2 ON T1.n_regionkey = T2.r_regionkey INNER JOIN supplier AS T3 ON T1.n_nationkey = T3.s_nationkey WHERE T2.r_name = 'EUROPE'