module Main where

import Data.Maybe (fromJust)
import Data.List
import Control.Monad
import qualified Data.ByteString.Char8 as BS

import qualified Data.Vector.Unboxed as VU
import qualified Data.Vector.Unboxed.Mutable as VUM

bytestr2Int = fst . fromJust . BS.readInt
getInt = bytestr2Int <$> BS.getLine
getIntL_H = map bytestr2Int. BS.words <$> BS.getLine
getIntL_V n = replicate n $ getInt
getInt2D n = replicate n $ getIntL_H

main :: IO ()
main = do
    [x,y] <- getIntL_H
    print . findPrimPair $ VU.fromList . factors $ gcd x y

findPrimPair vec = findPrimPairN vec $ VU.length vec - 1

findPrimPairN vec n 
    | 0 == length (findPrimPairCore vec n) = vec VU.! n
    | otherwise                            = findPrimPairN vec (n-1)

findPrimPairCore :: VU.Vector Int -> Int -> [()]
findPrimPairCore vec n = do
    tgt <- [0..(n-1)]
    guard ( 0 /= mod (vec VU.! n) (vec VU.! tgt) )
    pure ()

factors :: Int -> [Int]
factors n = [x | x <- [1..n], n `mod` x == 0]

prime :: Int -> Bool
prime n = factors n == [1, n]

primes :: Int -> [Int]
primes n = [x | x <- [2..n], prime x]
