CodeForces - 467A - A. George and Accommodation

题目连接：http://codeforces.com/problemset/problem/467/A

题目描述

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 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 Input

3

1 1

2 2

3 3

Sample Output

0

Sample Input

3

1 10

0 10

10 10

Sample Output

2

解题思路

想要住在一个房间里，那么只要房间剩余的空间 >=2 就可以了

AC代码

#include<iostream>
using namespace std;
int main () {
int n;
int p, q;
cin >> n;
int ans = 0;
while(n--) {
cin >> p >> q;
if(q - p >= 2) ans++;
}
cout << ans << endl;
return 0;
}