cf467A George and Accommodation

A. George and Accommodation

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

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.

Sample test(s)

input

3
1 1
2 2
3 3

output

0

input

3
1 10
0 10
10 10

output

2

sb题

判断qi-2>=pi的有多少个

#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std;
int n,m;
int main()
{
	scanf("%d",&n);
	int x,y;
	for(int i=1;i<=n;i++)
	{
		scanf("%d%d",&x,&y);
		if(y-x>=2)m++;
	}
	printf("%d",m);
	return 0;
}