There is a contest being held on Funmondi named ‘Funmondy Inter School Programming Contest’. You are one of the head organizers of this contest. So you have to keep track of so many things. One of them is how many different school student is currently present in the venue.
the third sample query input is 1 7. which means one student of school1 has left,one student of school7 has entered.
but it tells
" After the third query the present schools are: 1, 2, 3, 4, 5, 6, 8."
but how someone from school 7 just entered. why is there no school no 7?