\includegraphics{https://static.e-olymp.com/content/78/78ce88731f0771e8b7440ea23c74ef0cd569719f.jpg} \textbf{Pine forest. Pine Forest in the Vyatka province. 1872.} Kramskoy, each artist wrote of the "Pine forests", emphasizing full-scale accuracy of image: "The forest is wild and creek with glandular, dark-yellow water, which shows the entire bottom strewn with stones ..."However, it should be noted that at its Shishkin canvas several theatrical and forest landscape, offering a "spectacle of nature." Some people feel lucky number five. They throw a few bones, and if five drops more than one fifth of the bone, then the day is considered lucky. Throws \textbf{dice} the same bones, having the \textbf{sides} of the parties. Necessary to calculate the probability that the day will be happy. The probability of getting five at throwing dice with \textbf{sides} sides equal to \textbf{1 / sides}. \InputFile Each line is a separate test and contains the number of rolls the \textbf{dice} (\textbf{1} ≤ \textbf{dice} ≤ \textbf{20}) and the number of \textbf{sides} (\textbf{5} ≤ \textbf{sides} ≤ \textbf{10}) in them. \textbf{ Output} For each test on a separate line to derive the probability that the day will be happy. Probability output of \textbf{6} characters after the decimal point.