import sys; input = sys.stdin.buffer.readline
sys.setrecursionlimit(10**7)
from collections import defaultdict
con = 10 ** 9 + 7; INF = float("inf")

def getlist():
	return list(map(int, input().split()))

#処理内容
def main():
	X, Y = getlist()
	if X == Y:
		print(0)
	elif Y == 0:
		print(1)
	elif X == 0:
		print(2)
	elif abs(X) == abs(Y):
		print(3)
	else:
		print(-1)



if __name__ == '__main__':
	main()