3082: George and Accommodation
题目描述
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 George and Alex can move in.
3
1 1
2 2
3 3
0
3
1 10
0 10
10 10
2