Solve the programming task below in a Python markdown code block.
Read problems statements in Mandarin Chinese here

City of Byteland can be described as a $2D$ grid of cells. Each cell may or may not contain a demon. You are given the list of cells that contain demons.

In a single Kamehameha attack, Goku can kill all the demons standing in a row or in a column. But using Kamehameha drains Goku's power. You are to tell the minimum number of Kamehameha attacks that will be required by Goku to destroy all the demons.

------  Input ------
The first line contains a single integer $T$, the number of test cases. The description of the test cases follows.
The first line of each test case contains a single integer $N$, the number of cells where enemies are present. The description of the enemies follows.
The next $N$ lines contain two space separated integers $X$ and $Y$, the row and column of the cell in which a demon is present.

------  Output ------
For each test case, on a new line, print the minimum number of attacks that are required to kill all of the demons.

------  Constraints ------
$1 ≤ T ≤ 10$
$1 ≤ N ≤ 1000$
$1 ≤ X, Y ≤ 10^{9}$

----- Sample Input 1 ------ 
1
3
0 0
1 0
0 1
----- Sample Output 1 ------ 
2