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
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
For each test case print the floor expected time of wait.
1 <= t <= 10
1 <= n,x <= 100000
1 <= time required for a haircut <= 1000000
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