program main
  implicit none
  integer::N,D,i,curr,next
  integer,allocatable::ashiba(:)
  read *,N,D
  allocate(ashiba(0:N-1))
  ashiba = 1
  curr = 0
  do i=1,N
     ashiba(curr) = 0
     next = MOD(curr+D,N)
     if(ashiba(next).eq.0) exit
     curr = next
  end do
  i = MIN(N,i)
  print '(i0)',i
end program main