Migrated from Lutece 124 Tournament

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Description

A sports company is planning to advertise in a tournament. It is a single round-robin tournament, that's to say competitors play with all the others once. The company thinks that the advertising impact is proportional to the so called competitiveness degree(CD) of the tournament.

CD is calculated in the following way: We assume there're $N$ competitors in the tournament and of course $\frac{N\times (N - 1)}{2}$ matches in total. For each competitor we define two values $S$ and $E$ which stand for skill and experience. We say a match between competitor $i$ and competitor $j$ is competitive if and only if $S_i + E_i \geq S_j$ and $S_j + E_j \geq S_i$. CD equals to the number of competitive matches among all $\frac{N\times (N - 1)}{2}$ matches in the tournament.

Input

One integer $T$ ($T \leq 20$) on the first line indicates the number of cases. The first line of each case contains one integer $N$ ($1\leq N\leq 10000$) -- the number of competitors. Then $N$ lines follows. The $i_{th}$ line contains two integer $S_i$ and $E_i$ ($1\leq S_i, E_i\leq 100000000$) which are defined in the description.

Output

For each case, print the value of CD on a line.

Samples

3
2
1 2
4 1
2
1 2
2 2
5
1 9
5 4
3 4
2 2
6 2

0
1
8

Resources

The 8th UESTC Programming Contest Final