467_A. 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 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.

Input

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.

Output

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

Examples

Input

3
1 1
2 2
3 3


Output

0


Input

3
1 10
0 10
10 10


Output

2
```python
c = 0

for _ in range(int(input())):
    n = [int(x) for x in input().split()]
    n,m = n[0],n[1]

    if m - n >= 2:
        c += 1
print(c)

```