In a given array A find the maximum value of (A[i] – i) - (A[j] – j) where i is not equal to j.
i and j vary from 0 to n-1 and N is size of input array A. Value of N is always greater than 1.
The first line of input contains a single integer T denoting the number of test cases. Then T test cases follow. Each test case consist of two lines. The first line of each test case consists of an integer N, where N is the size of array.The second line of each test case contains N space separated integers denoting array elements.
Corresponding to each test case, in a new line, print the maximum value.
1 ≤ T ≤ 30
2 ≤ N ≤ 105
1 ≤ A[i] ≤ 105
9 15 4 12 13
3 1 2 4
(a-1) - (a-2) = (15-1)-(4-2) = 12
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