premise: Calvin has only visited Barbados, Christian has only visited Israel, Leon has only visited Ethiopia, Walter has only visited Lithuania, Nathan has only visited Equatorial Guinea, Howard has only visited Montenegro, Alfredo has only visited Monaco, Gabriel has only visited Pakistan, Dan has only visited São Tomé & Prícipe, Wesley has only visited Germany, Marion has only visited Timor-Leste, Peter has only visited Libya
hypothesis: Bob didn't visit Montenegro