{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE BangPatterns #-}

import Control.Applicative
import Control.Monad
import Control.Arrow
import Data.List
import Data.Maybe
import Data.Char
import Text.Printf

readInt = ( readLn :: IO Int )
getInts = map ( read :: String -> Int ) . words <$> getLine

which a b f = if f then a else b
mp [ a, b ] = ( a, b )

main = do
	[ p, q ] <- getInts
	print $ fromMaybe ( -1 ) $ solve p q

solve p 1 = Just ( p - 1 )
solve p q
	| g /= 1 = solve ( p `div` g ) ( q `div` g )
	| p < q = succ <$> solve q p
	| p == q = Nothing
	| otherwise = ( p `div` q + ) <$> solve ( p `mod` q ) q
		where g = gcd p q