CodeForces - 467A A. George and Accommodation

最新推荐文章于 2018-12-07 21:54:28 发布

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此算法帮助计算可供两位好友共同入住的宿舍数量。输入包括每个宿舍的当前人数及容量，输出为剩余床位足够两人的宿舍总数。

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.

Examples

input
3
1 1
2 2
3 3

output
0

input
3
1 10
0 10
10 10

output
2

题意：George跟Alex想住在同一个房间，统计所有房间内剩下的床位大于等于2个的

代码：

#include<cstdio>
int main() {
	int n,ans=0;
	scanf("%d",&n);
	for(int i=1;i<=n;i++){
		int a,b;
		scanf("%d%d",&a,&b);
		if(b-a>=2){
			ans++;
		}
	}
	printf("%d",ans);
	return 0;
}