A patient is 16 y.o. In the last year his behaviour has gradually changed: he secluded himself, was not interested in communication with friends, in learning. He became indifferent towards relatives, motivelessly rude, was speaking or laughing to himself. He answers the questions formally correctly, laconically. Considers himself to be absolutely healthy but a little tired, says, he's thinking about writing a book "Projection of humanity on the plane of Universe". He always has a copybook with which is full of a great many of the same daggers. What is the most