main = do
    content <- getContents
    putStrLn (show $ foldl getOp 0 (lines content))

getOp :: Int -> String -> Int
getOp acc number = acc + (math (read number)) + getFuel 0 (math(read number))

getFuel :: Int -> Int -> Int
getFuel acc fuel = do
	if (math fuel) > 0
           then acc + (math fuel) + getFuel acc (math fuel)
        else
           acc   

math :: Int -> Int
math input = ((input `div` 3) - 2)