A - George and Accommodation

最新推荐文章于 2018-12-07 21:54:28 发布

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最新推荐文章于 2018-12-07 21:54:28 发布

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原文链接：http://www.cnblogs.com/acgoto/p/9136342.html

本文介绍了一个简单的算法问题——计数空闲房间。题目要求找出哪些宿舍房间有足够的空间容纳新来的两名学生George和Alex。文章给出了清晰的解题思路，并提供了一段简洁的C++代码实现。

Problem description

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 p_i people living in it and the room can accommodate q_i people in total (p_i ≤ q_i). 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 p_i and q_i (0 ≤ p_i ≤ q_i ≤ 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

Output

Input

Output

2
解题思路：统计房间内剩余人数不小于2的房间总数（两个人住在同一间），水过！
AC代码：

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 int main(){
 4     int n,p,q,num=0;
 5     cin>>n;
 6     while(n--){
 7         cin>>p>>q;
 8         if(q-p>=2)num++;
 9     }
10     cout<<num<<endl;
11     return 0;
12 }