Virtual Judge第二题房间住人

George and Accommodation
CodeForces - 467A

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

挺随便的一道题
注意输入带空格其实实际上是有两个数据
主要问题是
注意有两个人一起住宿！

#include
using namespace std;

int main()
{
	int r,pi,qi,m=0;  //r代表room有多少间,pi代表房间目前有多少人住，qi代表房间可容纳多少人，m代表可以住进去的房间个数；
	cin >> r;
	for (int i = 0; i < r ; i++)  //反复输入pi，qi
	{
		cin >> pi >> qi;
		if ( pi <= qi-2)
		{

			m++;
		}
	}
	cout << m;
    return 0;
}