CF 467A George and Accommodation

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 hasp_i people living in it and the room can accommodateq_i people in total (p_i ≤ q_i). 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 p_i andq_i(0 ≤ p_i ≤ q_i ≤ 100) — the number of people who already live in thei-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：两个人去工作，希望在同一个房间并同时被叫到，问有几个房间满足；输入房间n，有两个属性，

           当前房间的人数和房间的总容纳量， 结构体相减就是可以容纳的，大于等于二就计数一次；

AC代码：

#include <bits/stdc++.h>using namespace std ;struct node {    int p;    int q;}a[500];int main(){    int n ;    scanf("%d",&n);    for(int i = 1 ; i<=n; i++)    {        scanf("%d %d",&a[i].p,&a[i].q);    }    int ans = 0 ;    for(int i = 1 ; i<=n ; i++)    {        int mini ;        mini = a[i].q - a[i].p ;        if(mini >=2 )            ans ++;    }    cout <<ans <<endl;    return 0 ;}