CREATE TABLE table_203_33 (id DECIMAL, "conference" TEXT, "date" TEXT, "place" TEXT, "attendance" DECIMAL, "archive of presentations" TEXT)

how many days was the wikimania 2011 ?
SELECT "date" - "date" FROM table_203_33 WHERE "conference" = 'wikimania 2011'
SELECT "date" - "date" FROM "table_203_33" WHERE "conference" = 'wikimania 2011'