x,y=map(int,input().split())
if x==y:
  print(0)
elif x==0 or y==0:
  ans=0
  while x!=y:
    if 0<=x<y:
      x,y=y,x
      ans+=1
    elif x==0 and y<0:
      x,y=y,x
      ans+=1
    X,Y=x+y,x-y
    x,y=X,Y
    ans+=1
  print(ans)
elif x+y==0:
  x,y=0,x-y
  if y<0:
    print(3)
  else:
    print(3)
else:
  print(-1)