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import Text.Megaparsec
import Data.Void (Void)
import Text.Megaparsec.Char
import Text.Megaparsec.Char.Lexer (signed, lexeme, decimal)
import System.Environment (getArgs)
import Data.Maybe (fromMaybe)
import Data.List ((\\))
smallestPositiveInteger :: [Int] -> Int
smallestPositiveInteger xs = head ([1..] \\ xs)
type Parser = Parsec Void String
parseArray :: Parser [Int]
parseArray = char '(' *> space *> sepBy (signed space (lexeme space decimal)) (char ',' <* space) <* char ')'
main :: IO ()
main = do
input <- fmap concat getArgs
let array = parseMaybe parseArray input
let array' = fromMaybe [1..] array
putStrLn $ show $ smallestPositiveInteger array'
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