import sys
input=lambda: sys.stdin.readline().rstrip()
x1,y1=map(int,input().split())
x2,y2=map(int,input().split())
x3,y3=map(int,input().split())
ans=x1
ct=0
chk=False
while ct<y2:
  if ans%y2==x2:
    chk=True
    break
  else:
    ans+=y1
    ct+=1
def gcd(a,b):
  while b:
    a,b=b,a%b
  return a
if chk==False:
  print(-1)
else:
  chk=False
  ct=0
  d=y1*y2//gcd(y1,y2)
  while ct<y3:
    if ans%y3==x3:
      chk=True
      break
    else:
      ans+=d
      ct+=1
  if chk:
    if ans==0:
      print(d*y3//gcd(d,y3))
    else:
      print(ans)
  else:
    print(-1)