import Data.List

main = interact counts

counts = unlines . collect 0 . foldr hist [] . map (length . words) . lines

hist x hs = case lookup x hs of 
    Just c -> insert (x,c+1) (filter ((/=x).fst) hs)
    Nothing -> insert (x,1) hs

collect n [] = []
collect n (x:xs) = let (f,r) = break ((>2^n).fst) (x:xs) 
                       s = sum $ map snd f
                   in ("2^"++show n++"\t"++show s) : collect (n+1) r