George and Accommodation
Time limit1000 ms
Memory limit262144 kB
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：一个学校有n个房间，看有多少个房间可以容纳他们两个人居住。
问题分析：用for循环和if语句判断有多少个房间能住两个人。
AC通过的C语言程序如下：
#include <iostream>
using namespace std;
int main()
{
int n, pi, qi, a = 0;
cin >> n;
for (int i = 0; i < n; i++)
{
cin >> pi >> qi;
if (qi - pi >= 2)
a++;
}
cout << a;
}