Alice and Bob have joined a competitive game! Initially, there are
slices of good
, and
slices of bad
. With Alice going first, they will take turns picking one of the slices of
uniformly at random and eating it. If a player eats a good slice of
, they gain one point, and if they eat a bad slice of
, they lose one point. After each turn, they will bake a good/bad slice of
to replace the type of
that was just eaten. Then, they will bake
additional slices of
, each with equal probability of being either good or bad.
Alice and Bob will spend the rest of eternity competing in this game! Determine the limit of the expected value of Alice's points minus Bob's points after
turns, as
approaches infinity. To ensure the integrity of your solution, there will be
testcases.
Constraints
Subtask 1 [27%]
Subtask 𝓮 [31%]
Subtask π [42%]
Input Specification
The first line contains one integer, , the number of testcases.
The next lines each contain three space-separated integers,
,
, and
, describing each testcase.
is the initial number of good slices of
,
is the initial number of bad slices of
, and
is the number of randomly good/bad
slices which are added after each turn. It is guarenteed that there is at least one slice of
initially.
Output Specificiation
Output lines, the
line containing one real number, the answer to the
testcase. Your answers will be considered correct if their absolute error is less than
.
Sample Input
3
1 0 2
2 4 3
5 2 4
Sample Output
0.7853981633974483
-0.20456854629336979
0.2687567584009584
Explanation for Sample
For the first testcase, it can be shown that the limit of the expected value approaches
For the second testcase, it can be shown that the limit of the expected value approaches
For the third testcase, it can be shown that the limit of the expected value approaches
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