import Control.Applicative ((<$>))

isKadoSeq :: (Integral a, Ord a) => [a] -> Bool
isKadoSeq xs @ (a : b : c : []) = c1 && c2
    where
        c1 = a /= b && b /= c && c /= a
        c2 = b == (maximum xs) || b == (minimum xs)
isKadoSeq _ = False

countP :: (Integral a, Ord a) => [a] -> Maybe a
countP xs
    | isKadoSeq xs = Nothing
    | otherwise = Just $ sum [1 | p <- [1 .. maximum xs], isKadoSeq $ map (`mod` p) xs]

main :: IO ()
main = do
    xs <- map read . words <$> getLine
    case countP xs of
        Just n -> print n
        Nothing -> putStrLn "INF"