module Main where

import Stail
import System.Environment

data StailOption = Stail | Stail2 | Stail2Fold deriving Read

main :: IO ()
main =
  do
    args <- getArgs
    case args of
      ostr:nstr:_ ->
        let o = read ostr :: StailOption
            n = read nstr :: Integer
            l = [1..(n ^ 2)] 
            helper h =
             putStrLn $ (case h l of
                         Nothing -> "empty"
                         Just [] -> "singleton"
                         Just _ -> "at least two elements") 
        in
          case o of
            Stail -> helper stail
            Stail2 -> helper stail2
            Stail2Fold ->
             putStrLn $ (case stail2Fold l of
                         Nothing -> "empty"
                         Just (_ , []) -> "singleton"
                         _ -> "at least two elements") 
             

      _ -> putStrLn "Run with one command-line argument, a list length"