n = 3
a = 0
b = 1

def extgcd(x,y):
  if y == 0: return (x,1,0)
  g,a,b = extgcd(y,x%y);
  return (g,b,a-x//y*b)

def factor(x):
  r = []
  i = 2
  while i*i < x:
    while x%i == 0:
      r.append(i)
      x /= i
    i += 1
  if x != 1: r.append(x)
  return r

def f(x,p):
  r = 1
  while x%p == 0:
    x /= p
    r *= p
  return r

def fail():
  print -1
  exit(0)

for ti in xrange(n):
  na,nb = map(int,raw_input().split())
  g = extgcd(b,nb)[0]
  if a%g != na%g: fail()
  for p in factor(g):
    p1 = f(b,p)
    p2 = f(nb,p)
    if p1 < p2:
      b /= p1
      a %= b
    else:
      nb /= p2
      na %= nb
  x,y = extgcd(b,nb)[1:]
  a = x*b*na + y*nb*a
  b *= nb
  a %= b

if a == 0: a = b
print a