CREATE TABLE table_19526911_1 (arena__capacity_ VARCHAR2, head_coach VARCHAR2)

What is the arena capacity of the arena in the town whose head coach is Roberto Serniotti?
SELECT arena__capacity_ FROM table_19526911_1 WHERE head_coach = "Roberto Serniotti"
SELECT "arena__capacity_" FROM "table_19526911_1" WHERE "Roberto Serniotti" = "head_coach"