As you were walking in the small corridor of your high school, you heard music from a classroom. Intrigued, you opened the door of this room. You stepped in. Your attention instantly went on a tall boy. He was playing «clair de lune» by Debussy on a big black piano. His hands seemed to be dancing on the keyboard. After a few seconds of watching him, he stops playing and ask with a formal voice

-Who's there ?