filter-positions-in-a-list.hs

f :: [Int] -> [Int]
f x= map snd $ filter (even.fst) $ zip [1..] x

-- This part deals with the Input and Output and can be used as it is. Do not modify it.
main = do
  inputdata <- getContents
  mapM_ (putStrLn. show). f. map read. lines $ inputdata