ACM训练题-第二题-George and Accommodation

Time limit1000 msMemory limit262144 kB
total：Time 31ms Memory 8kB

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

问题链接：https://vjudge.net/problem/CodeForces-467A
问题简述：乔治和亚历克斯希望住在同一个房间里。宿舍共有n个房间。
目前第i个房间里有pi人居住，房间总共可以容纳qi人（pi≤qi）。
您的任务是计算乔治和亚历克斯有多少间客房可以选择。
程序说明：算法就是计算qi>pi有多少次
AC通过的C++语言程序如下：
#include
using namespace std;
int main()
{
int n, i, j, sum = 0;
cin >> n;
while (n > 0)
{
cin >> i >> j;
if (j - i > 1) sum++;
n–;
}
cout << sum;
}