410682: GYM104076 H Set of Intervals

Prof. Pang has a multi-set of intervals $$$S=\{[l_i,r_i]\}$$$($$$l_i<r_i$$$).

Prof. Pang will perform the following operation for $$$|S|-1$$$ times:

• Select two intervals $$$[a,b]$$$ and $$$[c,d]$$$ from $$$S$$$, and then choose two integers $$$x,y$$$ satisfying $$$x\in [a,b], y\in [c,d], x<y$$$. After that, delete $$$[a,b]$$$ and $$$[c,d]$$$ from $$$S$$$, and add $$$[x,y]$$$ to $$$S$$$.

It's easy to find that $$$S$$$ contains exactly one interval after the operations, and Prof. Pang will get the interval as a gift.

Now Prof. Pang wants you to calculate how many different intervals he can get.

The first line contains one integer $$$T$$$ ($$$1\le T \le 10^4$$$), the number of test cases.

For each test case, the first line contains one integer $$$n$$$ ($$$1\le n\le 10^5$$$) — the size of $$$S$$$. Each of the following $$$n$$$ lines contains two integers $$$l_i$$$ and $$$r_i$$$ ($$$1\le l_i<r_i\le 10^9$$$), describing the $$$i$$$-th interval in $$$S$$$.

It is guaranteed that the sum of $$$n$$$ over all test cases is no more than $$$10^5$$$.

For each test case, output one line containing the answer to Prof. Pang's question.

4
1
1 1000000000
2
1 1000000000
1 1000000000
4
1 2
3 4
5 6
7 8
4
1 3
2 4
5 8
6 7

1
499999999500000000
26
28