CF467A George and Accommodation

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 $ p_{i} $ people living in it and the room can accommodate $ q_{i} $ people in total ( $ p_{i}

The first line contains a single integer $ n $ $ (1

Print a single integer — the number of rooms where George and Alex can move in.