|Codeforces Round #267 (Div. 2)|
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.