thread_num = omp_get_num_threads ( )
  solution_num = 0
!$omp parallel private ( i, ilo, ihi, j, value, x ) &
!$omp shared ( n, thread_num ) &
!$omp reduction ( + : solution_num )
  id = omp_get_thread_num ( )
  ilo = id * 65536 / thread_num
  ihi = ( id + 1 ) * 65536 / thread_num

  j = ilo
  do i = n, 1, -1
    x(i) = mod ( j, 2 )
    j = j / 2
  end do

  do i = ilo, ihi - 1
    value = circuit_value ( n, x )
    if ( value == 1 ) then
      solution_num = solution_num + 1
      write ( *, '(2x,i2,2x,i10,3x,16i2)' )  solution_num, i - 1, x(1:n)
    end if
    call bvec_next ( n, x )
  end do
!$omp end parallel