Codeforces刷题之路——467A George and Accommodation

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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

解题思路：这是一道水题，大致意思为求出能同时入住George和Alex的房间有多少间。

以下为解题代码 (java实现)

import java.util.Scanner;
public class Main {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner scanner = new Scanner(System.in);
int n = scanner.nextInt();
int count = 0;
int p = 0;
int q = 0;
for(int i = 0; i < n;i++){
p = scanner.nextInt();
q = scanner.nextInt();
scanner.nextLine();
if((q-p) >= 2){
count++;
}
}
System.out.println(count);
}
}