Instruct: Classify the given review as either positive or negative.
Query: This book is not serious

I rely don't know how someone cam believe that what is in this book is serious. To say that people here fight against each other with knives is silly, it just don't happen. The book has nothing useful.I hope nobody tries to use the stuff in the book for real. It is also verry strange the number of people in one day saying good things about the book. Acre it is not so different them country side of Minas Gerais, a lot of people get killed by knives but is in not fights.Luís Felipe Barbosa Moreira