diff --git a/Haskell/Main.hs b/Haskell/Main.hs
@@ -10,7 +10,7 @@ import Numeric.Natural
import System.Environment
import System.Exit
import Control.Monad (foldM)
-import Data.Vector (Vector, unsafeIndex, generate, (!))
+import Data.Vector (Vector, unsafeIndex, generate)
main :: IO Int
main = do
@@ -19,6 +19,7 @@ main = do
case readDec <$> head' args of
Just [(max, "")] ->
if counterexempl max then exitFailure else exitSuccess
+
_ -> exitInvalidInput
where head' [] = Nothing