premise: Sergio has only visited Burundi, Lance has only visited Suriname, Alberto has only visited Afghanistan, Henry has only visited Ireland, Dan has only visited Sierra Leone, Virgil has only visited China, Erik has only visited Bhutan, Perry has only visited Malawi, Bryan has only visited Liechtenstein, Manuel has only visited Equatorial Guinea, Tony has only visited Malta, Aaron has only visited Laos
hypothesis: Dan didn't visit Sierra Leone