Nested_Dolls(偏序集)

Nested Dolls

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 3570		Accepted: 949

Description

Dilworth
is the world's most prominent collector of Russian nested dolls: he
literally has thousands of them! You know, the wooden hollow dolls of
different sizes of which the smallest doll is contained in the second
smallest, and this doll is in turn contained in the next one and so
forth. One day he wonders if there is another way of nesting them so he
will end up with fewer nested dolls? After all, that would make his
collection even more magnificent! He unpacks each nested doll and
measures the width and height of each contained doll. A doll with width
w
1
and height h
1
will fit in another doll of width w
2
and height h
= if and only if w
1
< w
2
and h
1
< h
2
. Can you help him calculate the smallest number of nested dolls possible to assemble from his massive list of measurements?

Input

On the first line of input is a single positive integer 1 ≤ t
≤ 20 specifying the number of test cases to follow. Each test case begins with a positive integer 1 ≤ m
≤ 20000 on a line of itself telling the number of dolls in the test case. Next follow 2m
positive integers w
1
, h
1
,w
2
, h
2
, ... ,wm

, hm

, where wi

is the width and hi

is the height of doll number i
. 1 ≤ wi

, hi

≤ 10000 for all i
.

Output

For each test case there should be one line of output containing the minimum number of nested dolls possible.

Sample Input

4

3

20 30 40 50 30 40

4

20 30 10 10 30 20 40 50

3

10 30 20 20 30 10

4

10 10 20 30 40 50 39 51

Sample Output

1

2

3

2

Source
Nordic 2007