main = do
  n <- getLine
  a <- map read . words <$> getLine
  putStrLn . show $ solve a



solve :: [Integer] -> Integer
solve xs =
  let absed = map abs xs
      minabs = minimum absed
      m = minusCnt xs
      z = zeroCnt xs
  in if m `mod` 2 == 0 || (m+z) `mod` 2 == 0 then
    sum absed
  else
    sum absed - (2*minabs)

minusCnt :: [Integer] -> Int
minusCnt = length . filter (\x -> x < 0)

zeroCnt :: [Integer] -> Int
zeroCnt = length . filter (\x -> x == 0)
