Description

A new Semester is coming and students are troubling for selecting courses. Students select their course on the web course system. There are n courses, the i

^th

course is available during the time interval (A

_i

,B

_i

). That means, if you want to select the i

^th

course, you must select it after time A

_i

and before time B

_i

. A

_i

and B

_i

are all in minutes. A student can only try to select a course every 5 minutes, but he can start trying at any time, and try as many times as he wants. For example, if you start trying to select courses at 5 minutes 21 seconds, then you can make other tries at 10 minutes 21 seconds, 15 minutes 21 seconds,20 minutes 21 seconds… and so on. A student can’t select more than one course at the same time. It may happen that no course is available when a student is making a try to select a course

You are to find the maximum number of courses that a student can select.

Input

There are no more than 100 test cases.

The first line of each test case contains an integer N. N is the number of courses (0 < N <= 300) Then N lines follows. Each line contains two integers A_i

and B

_i

(0 <= A

_i

< B

_i

<=1000), meaning that the i

^th

course is available during the time interval (A

_i

,B

_i

).

The input ends by N = 0.

Output

For each test case output a line containing an integer indicating the maximum number of courses that a student can select.

2
1 10
4 5
0

2

Source