Who was Yuri? How did he help Albert in getting rid of the school?

Yuri was Albert’s friend living in Munich. He is Albert’s only friend. Albert tells him everything about his life. He tells Yuri that he doesn’t like to go to school. He asks Yuri if he has a doctor friend. He plans to get a medical certificate from a doctor, which shall certify that Albert suffers from a nervous breakdown. This will enable him to leave school for some period. Yuri tells him that he knows Dr. Ernest Weil who has qualified as a doctor last week. Yuri fixes an appointment with him and tells Albert to tell the doctor everything. So, Albert tells the doctor everything. Dr. Ernest Weil issues him a certificate. His fees is that Albert shall host a dinner to Yuri. While leaving the city, Yuri advises Albert to get a certificate from Maths teacher Mr. Koch so that he can get admission in same Italian college.