main :: IO ()
main = print $ fst $ head $ dropWhile ((< 500) . snd) triDivs
    where triDivs = map (countDivs . (\n -> n*(n+1)`div`2)) $ [5..]
main :: IO ()
main = print $ fst $ head $ dropWhile ((< 500) . snd) triDivs
    where triDivs = map (countDivs . (\n -> n*(n+1)`div`2)) $ [5..]
main = print $ fst $ head $ dropWhile ((< 500) . snd) triDivs
    where triDivs = map (countDivs . (\n -> n*(n+1)`div`2)) $ [5..]