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

31 12 23 3

output

0

input

31 100 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;
}