This is your first day in your new school. You have math class, which is very boring. The girl sitting behind you touches your shoulder and you turn over. She gives you a crumpled up paper. You accept it and turn back. The paper says "Call me 'phone number' Nikola" You look around the class, but you have no idea who Nikola is. After school, you go home and you only can think about the phone number. Who can it be?