Average Temperature Calculation

You are given temperature readings over several days. Some readings may be missing, which are represented by the value -9999. Your task is to compute the average temperature from the valid readings. If all readings for a test case are missing, output -9999.

The average temperature is computed as:

\( \text{average} = \frac{\sum_{i=1}^{k} T_i}{k} \)

where \(T_i\) are the valid temperature readings and \(k\) is the number of valid readings. Round the result to 2 decimal places.

Note: Process multiple test cases from standard input.

inputFormat

The first line of input contains an integer T representing the number of test cases. Each test case consists of two lines:

• The first line contains an integer n, the number of days.
• The second line contains n space-separated integers representing the temperature readings. A reading of -9999 indicates missing data.

Input is read from standard input.

outputFormat

For each test case, output the average temperature on a new line. If there are valid temperature readings, output the average rounded to 2 decimal places. If all readings in a test case are missing, output -9999.

Output should be written to standard output.

## sample

4
5
20 25 -9999 30 18
4
-9999 -9999 -9999 -9999
6
-9999 15 19 21 -9999 30
5
20 25 30 18 22

23.25
-9999
21.25
23.0

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