{-# LANGUAGE BangPatterns #-} {-# LANGUAGE BinaryLiterals #-} {-# LANGUAGE MultiWayIf #-} {-# LANGUAGE NumDecimals #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TupleSections #-} import Control.Applicative import Control.Arrow import Control.Monad import Control.Monad.ST import Data.Char import Data.List import Data.Maybe import qualified Data.ByteString.Char8 as B import Data.Array.ST.Safe import Data.STRef import Debug.Trace import Text.Printf readInt = readLn :: IO Int readInts = map ( fst . fromJust . B.readInt ) . B.words <$> B.getLine readNInts = readInt >>= flip replicateM readInt which a b f = if f then a else b mp [ a, b ] = ( a, b ) main = do [ a, b ] <- readInts let res = filter ( f a b ) $ takeWhile ( \i -> i * i <= a + b ) [ 1 .. ] print $ if null res then -1 else head res f a b c = ( a + b ) `mod` c == 0 && ( a + c ) `mod` b == 0 && ( b + c ) `mod` a == 0