digit36 :: Char -> Int
digit36 x | x `elem` ['0'..'9'] = (ord x) - (ord '0')
          | x `elem` ['A'..'Z'] = (ord x) - (ord 'A')  + 10
          | x `elem` ['a'..'z'] = (ord x) - (ord 'a')  + 10

base36 :: String -> Int
base36 x = fst $ head $ readInt 36 (`elem` ['0'..'1']++['a'..'z']++['A'..'Z']) digit36 x