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.

**Input:**

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.

**Output:**

Corresponding to each test case, in a new line, print the maximum value.

**Constraints:**

1 ≤ T ≤ 100

2 ≤ N ≤ 200

1 ≤ A[i] ≤ 1000

**Example:**

**Input**

1

5

9 15 4 12 13

**Output**

12

**Explanation**

(a[1]-1) - (a[2]-2) = (15-1)-(4-2) = 12

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