CF 467A-George and Accommodation

CF 467A
A. George and Accommodation

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
1 100 1010 10

output

2

题意：n组测试，每组两个数，pi和qi。pi是一个房间里住了几个人，qi是一个房间能住几个。问有几个房间能加进去两个人。

思路：水。

#include<stdio.h>

#include<math.h>

int main()

{

    int n,sum,pi,qi;

    scanf("%d",&n);

    sum=0;

    while(n--)

    {

        scanf("%d%d",&pi,&qi);

        if(qi-pi>=2) sum++;

    }

    printf("%d\n",sum);

    return 0;

}