func main()
	var _: [][]char :: cui@input().split(" ")
	var A: int :: _[0].toInt(&)
	var B: int :: _[1].toInt(&)
	var ans: int
	if(A = B)
	elif(A > B)
		do ans :: 2000000000 - B - 1
	else
		do ans :: B - 2
	end if
	do cui@print("\{ans}\n")
end func