readI :: String -> Maybe Int
readI s =
  case reads s of
    ((v,_):_) -> Just v
    _ -> Nothing
readI :: String -> Maybe Int
readI s =
  case reads s of
    ((v,_):_) -> Just v
    _ -> Nothing
readI s =
  case reads s of
    ((v,_):_) -> Just v
    _ -> Nothing