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 ( $p_{i}<=q_{i}$ ). 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 $p_{i}$ and $q_{i}$ $(0<=p_{i}<=q_{i}<=100)$ — 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 George and Alex can move in.