# -*- coding: utf-8 -*-
#yuki_186
import sys

def gcd(a, b):
 while b:
  a, b = b, a%b
 return a

def lcm(a,b):
 return a/gcd(a,b)*b


x1,y1=map(int,raw_input().split())
x2,y2=map(int,raw_input().split())
x3,y3=map(int,raw_input().split())

for i in xrange(y2):
 a0=y1*i+x1
 if a0==0:
  continue
 if (a0-x2)%y2==0:
  for j in xrange(y3):
   res=a0+j*lcm(y1,y2)
   if (res-x3)%y3==0:
    print res
    sys.exit()
 
print -1