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.

输入描述:

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.

输出描述:

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