import Control.Monad
import Text.Printf

main :: IO ()
main = do
  t <- readLn
  forM_ [(1::Int)..t] $ \i -> do
    [a,b] <- liftM (map read . words) getLine
    ps <- liftM (map read . words) getLine
    let ans = solve a b ps
    printf "Case #%d: %.7f\n" i ans

solve :: Int -> Int -> [Double] -> Double
solve a b ps = minimum $ opt3 : opt2
  where
    opt3 = fromIntegral $ 1 + b + 1
    opt2 = do
      (n, p) <- zip [0..] (scanl (*) 1 ps)
      return $ fromIntegral (a - n + b - n + 1) + (1 - p) * fromIntegral (b + 1)