-- Try yukicoder
-- author: Leonardone @ NEETSDKASU

import Data.List (sort)

main = interact $ show . solve . sort . map read . words

solve :: [Double] -> Double

solve [p, a, b]
    | b == 1    = p
    | a == 1    = p * p * (2 + p * (b - 2))
    | otherwise = p * p * p * (4 + p * (2 * (a - 2 + b - 2) + p * (a - 2) * (b - 2)))

solve _ = undefined