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 < 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.