A16416. 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, $a_i < b_i$ , 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.

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 $b_i$ ( $-10^9 \leq a_i < b_i \leq 10^9$ ) — 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 $2 \cdot 10^5$ .

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

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