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 $*p*_{*i*}$ 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.