| Author: | G. Grenkin | Time limit: | 1 sec | |
| Input file: | input.txt | Memory limit: | 256 Mb | |
| Output file: | output.txt |
Once upon a time Marfa Gennadievna bought a pack of 54 playing cards containing two jokers. She put cards face down and chose N cards of them randomly (with uniform probability distribution).
Your program must calculate the probability that there will be at least one joker among chosen cards.
Input file contains a single integer N.
Output file must contain a single real number — required probability with at least 6 correct digits after decimal point.
2 ≤ N ≤ 54
| No. | Input file (input.txt) |
Output file (output.txt) |
|---|---|---|
| 1 | |
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| 2 | |
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