George has recently entered the BSUCP (Berland State University for Cool Programmers).George has a friend Alex who has also entered the university. Now they are moving into a dormitory.
George and Alex want to live in the same room. The dormitory has N rooms in total. At the moment the i-th room has Pi people living in it and the room can accommodate qi people in total(pi <= qi). Your task is to count how many rooms has free place for both George and Alex.
The first line contains a single integer N (1 <= N <= 100) ---- the number of rooms.
The i-th of the next N lines contains two integers pi and qi (0 <= pi <= qi <= 100) the number of people who already live in the i-th room and the room's capacity.
Print a single integer -- the number of rooms where Grorge and Alex can move in.
3 1 1 2 2 3 3 3 1 10 0 10 10 10