# Practice on Toph

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# Coin Toss

By · Limits 1s, 512 MB

Sanvi is playing with a coin in which number 1 is written on the top side and number 0 is written at the bottom side. She is planning to toss the coin exactly N times. What is the probability that summation of coin tosses will either be A or B ? Your task is to help her find the answer.

## Input

Input starts with an integer T (1≤T≤100000) denoting the total number of test-cases. Every test-case starts with N (1 ≤ N ≤ 30), denoting the total number of times coin is tossed. This is followed by a single line containing two different non-negative integer numbers having value at most N, separated by a single space, denoting A and B respectively. ( A!=B, 0<=A,B<=N )

## Output

For every case of input, output the answer in a single line denoting the answer as described in the problem statement. Error less than 10-6 will be ignored.

## Sample

InputOutput
```2
1
0 1
2
2 1
```
```1.000000
0.750000
```

Discussion
Statistics

81% Solution Ratio

NirjhorEarliest, Jul '18

fsshakkhorFastest, 0.1s

flash_7Lightest, 1.0 MB

tuxboyShortest, 416B

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