Subrectangle Guess

Description:

Input:

Each test contains multiple test cases. The first line contains the number of test cases $$$t$$$ ($$$1 \le t \le 20$$$). Description of the test cases follows.

The first line of each test case contains two integers $$$n$$$ and $$$m$$$ ($$$1 \le n, m \le 40$$$)  — the size of the grid.

Each of the following $$$n$$$ lines contains $$$m$$$ integers. The $$$j$$$-th integer on the $$$i$$$-th line is $$$a_{ij}$$$ ($$$-10^9 \le a_{ij} \le 10^9$$$)  — the element in the cell $$$(i, j)$$$.

It is guaranteed that all the numbers are distinct (that is, if $$$a_{i_1j_1} = a_{i_2j_2}$$$, then $$$i_1 = i_2, j_1 = j_2$$$).

Output:

For each test case print a single positive integer  — the minimum possible area the subrectangle can have while still ensuring that Michael can guarantee the victory.

Sample Input:

3
1 1
3
4 4
2 12 6 10
3 15 16 4
1 13 8 11
14 7 9 5
2 3
-7 5 2
0 8 -3

Sample Output:

1
9
4

Note:

In the first test case, the grid is $$$1\times 1$$$, so the only possible choice for $$$h, w$$$ is $$$h = 1, w = 1$$$, giving an area of $$$h\cdot w = 1$$$.

The grid from the second test case is drawn in the statement. It can be shown that with $$$h = 3, w = 3$$$ Michael can guarantee the victory and that any choice with $$$h\cdot w \le 8$$$ doesn't.