{-# LANGUAGE TypeApplications #-}

import Data.List
import Data.Maybe
import Control.Monad

find_n_summing :: (Num a, Eq a) => a -> Int -> [a] -> Maybe [a]
find_n_summing to = (find ((to ==) . sum) .) . replicateM

main = do
    nums <- fmap read <$> lines <$> readFile "input.txt"
    mapM_ print $ product <$> fromJust <$> flip (find_n_summing 2020) nums <$> [2, 3]