Maximum Difference in Matrix

Given an n x n matrix mat[n][n] of integers, find the maximum value of mat[c][d] - mat[a][b] for all possible indices where c > a and d > b.

Input:

The first line contains a single integer T representing the number of test cases. For each test case:
The first line contains a single integer N denoting the size of the matrix.
The next N lines contain 'N' integers each, where each line represents a row of the matrix.

Output:

For each test case, output a single integer indicating the maximum difference calculated for that test case.
Each result should be printed on a new line.

Example:

Input:

1
3
1 2 3
4 5 6
7 8 9

Output:

8

Explanation:

In this matrix, the maximum difference is 8 (from mat[2][2] - mat[0][0]).

Constraints:

• 1 ≤ N ≤ 100
• 1 ≤ mat[i][j] ≤ 108

Note:

No need to print in your solution, just implement the function.