CREATE TABLE table_204_859 (id NUMBER, "year" NUMBER, "seniors  ( trood award & rodda medal ) " CLOB, "reserves  ( rex hartley medal ) " CLOB, "under 18's  ( bruce wilkinson medal ) " CLOB, "under 16's  ( shaw/carter medal ) " CLOB)

how many different people were reserves before tom hart ?
SELECT COUNT(DISTINCT "reserves (rex hartley medal)") FROM table_204_859 WHERE "year" < (SELECT "year" FROM table_204_859 WHERE "reserves (rex hartley medal)" = 'tom hart')
SELECT COUNT(DISTINCT "reserves (rex hartley medal)") FROM "table_204_859" WHERE "year" < (SELECT "year" FROM "table_204_859" WHERE "reserves (rex hartley medal)" = 'tom hart')