CF1915F.Greetings

There are $n$ people on the number line; the $i$-th person is at point $a_i$ and wants to go to point $b_i$. For each person, $a_i \lt b_i$, and the starting and ending points of all people are distinct. (That is, all of the $2n$ numbers $a_1, a_2, \dots, a_n, b_1, b_2, \dots, b_n$ are distinct.)

All the people will start moving simultaneously at a speed of $1$ unit per second until they reach their final point $b_i$. When two people meet at the same point, they will greet each other once. How many greetings will there be?

Note that a person can still greet other people even if they have reached their final point.

数轴上有 $n$ 个人；第 $i$ 个人起始于位置 $a_i$，目标是到达位置 $b_i$。对每个人而言，均有 $a_i \lt b_i$，且所有人的起点与终点互不相同（即全部 $2n$ 个数 $a_1, a_2, \dots, a_n, b_1, b_2, \dots, b_n$ 两两不同）。

所有人将同时以每秒 $1$ 单位的速度出发，持续移动直至抵达各自的目标点 $b_i$。当两人在同一时刻到达同一位置时，他们彼此致意一次。问：总共会发生多少次致意？

注意：即使某人已抵达其目标点，他仍可与其他尚未抵达目标点（或也已抵达）的人致意。

The first line of the input contains a single integer $t$ ($1 \le t \le 10^4$) — the number of test cases. The description of test cases follows.

The first line of each test case contains a single integer $n$ ($1 \le n \le 2 \cdot 10^5$) — the number of people.

Then $n$ lines follow, the $i$-th of which contains two integers $a_i$ and $b_i$ ($-10^9 \leq a_i \lt b_i \leq 10^9$) — the starting and ending positions of each person.

For each test case, all of the $2n$ numbers $a_1, a_2, \dots, a_n, b_1, b_2, \dots, b_n$ are distinct.

The sum of $n$ over all test cases does not exceed $2 \cdot 10^5$.

输入的第一行包含一个整数 $t$（$1 \le t \le 10^4$），表示测试用例的数量。随后是各测试用例的描述。

每个测试用例的第一行包含一个整数 $n$（$1 \le n \le 2 \cdot 10^5$），表示人数。

接下来是 $n$ 行，其中第 $i$ 行包含两个整数 $a_i$ 和 $b_i$（$-10^9 \leq a_i \lt b_i \leq 10^9$），分别表示第 $i$ 个人的起始位置和终止位置。

对于每个测试用例，所有 $2n$ 个数 $a_1, a_2, \dots, a_n, b_1, b_2, \dots, b_n$ 互不相同。

所有测试用例的 $n$ 值之和不超过 $2 \cdot 10^5$。

For each test case, output a single integer denoting the number of greetings that will happen.

对于每个测试用例，输出一个整数，表示将发生的问候次数。

In the first test case, the two people will meet at point $3$ and greet each other.

在第一个测试用例中，两人将在点 $3$ 相遇并互相问候。