def gcd(x, y):
	if y == 0:
		return x
	else:
		return gcd(y, x%y)


def extgcd(a,b):
	if b == 1:
		return (0,1)
	else:
		t = extgcd(b,a%b)
		return (t[1], t[0]-a//b*t[1])

def solve(x0,y0,x1,y1):
	c = x0-x1
	a = y0
	b = -y1
	if c < 0:
		a = -a
		b = -b
	sm0 = 1
	sm1 = 1
	if a < 0:
		sm0 = -1
	if b < 0:
		sm1 = -1
	g = gcd(sm0*a,sm1*b)
	# print(c)
	if c != 0:
		if c%g != 0:
			return (-1,-1)
		ps = extgcd(sm0*a//g,sm1*b//g)
		# print(ps)
		ps = (ps[0]*sm0*c//g,ps[1]*sm1*c//g)
		# ps[1] = ps[1]*sm1*c//g
		ho = sm1*b//g
		ge = ps[0]
		return (ho*y0, x0+y0*ge)
	else:
		return (y0*sm1*b//g, x0)

if __name__ == '__main__':
	x = []
	y = []
	for i in range(3):
		a,b = map(int,input().split())
		x.append(a)
		y.append(b)
	s1 = solve(x[0],y[0],x[1],y[1])
	# print(s1)
	if s1[0] == -1:
		print(-1)
		exit()
	s2 = solve(s1[1],s1[0],x[2],y[2])
	if s2[0] == -1:
		print(-1)
		exit()
	# print(s2)
	print(s2[1]%s2[0])