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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 Grorge and Alex can move in.

```
3
1 1
2 2
3 3
3
1 10
0 10
10 10
```

```
0
2
```