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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 2010-2021 Mike Mirzayanov

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