CREATE TABLE table_23068 ("Previous season 2007/2008" TEXT, "Team" TEXT, "Town" TEXT, "Arena  ( capacity ) " TEXT, "Website" TEXT, "Head Coach" TEXT, "Foreign Players  ( max. 2 ) " TEXT)

What is the arena capacity of the arena in the town whose head coach is Roberto Serniotti?
SELECT "Arena (capacity)" FROM table_23068 WHERE "Head Coach" = 'Roberto Serniotti'
SELECT "Arena (capacity)" FROM "table_23068" WHERE "Head Coach" = 'Roberto Serniotti'