codeforces467-A水題

題目連接：http://codeforces.com/problemset/problem/467/A

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

Copy

3
1 1
2 2
3 3

output

Copy

0

input

Copy

3
1 10
0 10
10 10

output

Copy

2

#include<iostream>
using namespace std;

int main()
{
    int n,p,q,num = 0;
    cin >> n;
    while(n--)
    {
        cin >> p >> q;
        if(q - p >= 2)
            num++;
    }
    cout << num << endl;
    return 0;
}