import Data.List

rInt :: String -> Int
rInt = read

allStones x y = x * 2 + y

solve xs
    | all (< 3) xs && elem 0 xs = [0,0,0]
    | elem 0 xs = solve $ sort $ elaseZero xs
    | otherwise = xs
    where
        elaseZero [x,y,z] = [1 , y, (z - 2)]

main = do
    stones <- solve . sort . map rInt . words <$> getLine
    print $ foldr allStones (last stones) (init stones) `div` 5