5406：CRB and Apple

In Codeland there are many apple trees.
One day CRB and his girlfriend decided to eat all apples of one tree.
Each apple on the tree has height and deliciousness.
They decided to gather all apples from top to bottom, so an apple can be gathered only when it has equal or less height than one just gathered before.
When an apple is gathered, they do one of the following actions.
1.  CRB eats the apple.
2.  His girlfriend eats the apple.
3.  Throw the apple away.
CRB(or his girlfriend) can eat the apple only when it has equal or greater deliciousness than one he(she) just ate before.
CRB wants to know the maximum total number of apples they can eat.
Can you help him?

There are multiple test cases. The first line of input contains an integer $T$, indicating the number of test cases. For each test case:
The first line contains a single integer $N$ denoting the number of apples in a tree.
Then $N$ lines follow, $i$-th of them contains two integers $H_{i}$ and $D_{i}$ indicating the height and deliciousness of $i$-th apple.
1 ≤ $T$ ≤ 48
1 ≤ $N$ ≤ 1000
1 ≤ $H_{i}$, $D_{i}$ ≤ $10^{9}$

For each test case, output the maximum total number of apples they can eat.