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 ) |
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1 |
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2 |
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