main = do
  li <- getLine
  let [a,b] = words li
  let ans = compute a b
  print ans

compute :: String -> String -> Integer
compute a b = a1 * (b1 * 100 + b2) `div` 100
  where
    a1 = read a
    b1 = read $ take 1 b
    b2 = read $ drop 2 b
