Read this and answer the question. If the question is unanswerable, say "unanswerable".

Bilateral treaties are concluded between two states or entities. It is possible, however, for a bilateral treaty to have more than two parties; consider for instance the bilateral treaties between Switzerland and the European Union (EU) following the Swiss rejection of the European Economic Area agreement. Each of these treaties has seventeen parties. These however are still bilateral, not multilateral, treaties. The parties are divided into two groups, the Swiss ("on the one part") and the EU and its member states ("on the other part"). The treaty establishes rights and obligations between the Swiss and the EU and the member states severallyit does not establish any rights and obligations amongst the EU and its member states.[citation needed]

Bilateral treaties are concluded between how many states or entities?
two