Read this: In 1949, the city was chosen to be the seat of the Council of Europe with its European Court of Human Rights and European Pharmacopoeia. Since 1952, the European Parliament has met in Strasbourg, which was formally designated its official 'seat' at the Edinburgh meeting of the European Council of EU heads of state and government in December 1992. (This position was reconfirmed and given treaty status in the 1997 Treaty of Amsterdam). However, only the (four-day) plenary sessions of the Parliament are held in Strasbourg each month, with all other business being conducted in Brussels and Luxembourg. Those sessions take place in the Immeuble Louise Weiss, inaugurated in 1999, which houses the largest parliamentary assembly room in Europe and of any democratic institution in the world. Before that, the EP sessions had to take place in the main Council of Europe building, the Palace of Europe, whose unusual inner architecture had become a familiar sight to European TV audiences. In 1992, Strasbourg became the seat of the Franco-German TV channel and movie-production society Arte.

How many days each month is Council of Europe business conducted in Brussels and Luxembourg?
What is the answer? (If it cannot be answered, return "unanswerable")
unanswerable