John's Haircut
##### Submissions: 1630   Accuracy: 16.32%   Difficulty: Easy   Marks: 2

Mr. John decides to have a haircut and goes to a barber shop. In the shop, he sees that there are n people waiting before him to have hair cut. He also notices a board which tells about diffrent types of haircut and time required for the hair designer to do that particular hair cut. Since John was very tired, he wanted to take a short nap before his turn. So he decides to set an alarm to wake up. Assuming each person is evenly likely for making a particular type of hair cut, help John to set alarm by telling him the floor of the expected time of wait.
NOTE: You can assume that when John sets alarm the hair designer starts his work for the first person

Input:
First line contains single integer 'T' denoting the number of test cases.First line of each test case contains two integers 'n' and 'x'
n - number of people waiting before John
x - number of types of haircut
Next line of the test-case contains x space separated integers, where ith integer denotes time taken for ith haircut

Output:
For each test case print the floor expected time of wait.

Constraints:
1 <= t <= 10
1 <= n,x <= 100000
1 <= time required for a haircut <= 1000000

Example:
Input:
1
1 2
10 8

Output:
9

#### ** For More Input/Output Examples Use 'Expected Output' option **

Author: kailashnath1998

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