Preparing NOJ

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*2 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?

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 2*m *positive integers*w*1*, h*1*, w*2*, h*2*, . . . , w**m**, h**m*, where *w**i *is the width and *h**i *is the height of doll number *i*.

1 *≤ **w**i**, h**i **≤ *10000 for all *i*.

For each test case there should be one line of output containing the minimum number of

nested dolls possible.

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

1

2

3

2

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本题由旧版NOJ导入，来源：Nordic Collegiate Programming Contest 2007