Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.
If you've seen these problems, a virtual contest is not for you - solve these problems in the archive.
If you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.
Never use someone else's code, read the tutorials or communicate with other person during a virtual contest.

No tag edit access

A. George and Accommodation

time limit per test

1 secondmemory limit per test

256 megabytesinput

standard inputoutput

standard outputGeorge 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 *p* _{ i} people living in it and the room can accommodate *q* _{ 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} and *q* _{ i} (0 ≤ *p* _{ i} ≤ *q* _{ i} ≤ 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

Codeforces (c) Copyright 2010-2020 Mike Mirzayanov

The only programming contests Web 2.0 platform

Server time: Aug/04/2020 21:00:54 (h1).

Desktop version, switch to mobile version.

Supported by

User lists

Name |
---|