Codeforces Round #267 (Div. 2) A

题目：

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

题意分析：

有N个寝室，每个寝室已经有p个人住了，总共能住下q个人。现在还有两个人能不能住下。直接写写写吧。大水题，看到一堆人1，2分钟就过了.

代码：

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>


using namespace std;


int main()
{
    int n,ans,q,p;
    while(scanf("%d",&n)!=EOF)
    {
       ans=0;
       for(int i=0;i<n;i++)
       {
           scanf("%d%d",&q,&p);
           if(p-q>=2)
            ans++;
       }
       printf("%d\n",ans);
    }
}