## Description:

Here N (N ≥ 3) rabbits are playing by the river. They are playing on a number line, each occupying a different integer. In a single move, one of the outer rabbits jumps into a space between any other two. At no point may two rabbits occupy the same position.

Help them play as long as possible

## Input:

The input has several test cases. The first line of input contains an integer t (1 ≤ t ≤ 500) indicating the number of test cases.

For each case the first line contains the integer N (3 ≤ N ≤ 500) described as above. The second line contains n integers $$$a_1$$$ < $$$a_2$$$ < $$$a_3$$$ < ... < $$$a_N$$$ which are the initial positions of the rabbits. For each rabbit, its initial position

$$$a_i$$$ satisfies 1 ≤ $$$a_i$$$ ≤ 10000.

## Output:

For each case, output the largest number of moves the rabbits can make.

## Sample Input:

5
3
3 4 6
3
2 3 5
3
3 5 9
4
1 2 3 4
4
1 2 4 5

## Sample Output:

1
1
3
0
1