Minimum Operations to Level Terrain

You are given a grid representing the heights of terrain cells. Your task is to determine the minimum number of operations required to level the terrain so that all cells have the same height. In one operation, you can choose one of the distinct heights present in the grid and change all cells of that height to match another existing height. It can be shown that the minimum number of operations required is equal to \(k - 1\), where \(k\) is the number of distinct heights in the grid.

Example: For a grid with heights:

1 2 3
2 3 4
3 4 5

There are 5 distinct heights, so the answer is \(5 - 1 = 4\).

inputFormat

The input is given via standard input (stdin) and has the following format:

T
m n
row1
row2
...
rowm
m n
row1
row2
...
rowm
...

Here, the first line contains an integer T, the number of test cases. Each test case starts with two integers m and n (the number of rows and columns of the grid, respectively), followed by m lines each containing n space-separated integers representing the heights of the terrain cells.

outputFormat

For each test case, output a single integer on a new line: the minimum number of operations required to make all the cells in the grid have the same height.

## sample

2
3 3
1 2 3
2 3 4
3 4 5
2 2
1 2
3 4

4
3

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