--?   io.stdout:write('---\n')

--?     dump_path(cand)

      local curr = level[y][x]
      if (y == empty_cell.y and x == empty_cell.x) or
          (not (y == occupied_cell.y and x == occupied_cell.x) and
           curr ~= CELL_WALL and
           curr ~= CELL_CRATE and
           curr ~= CELL_CRATE_ON_TARGET) then

      if is_empty(level, x,y, empty_cell, occupied_cell) then

function is_empty(level, x,y, empty, occupied)
  Real_print('aa', x,y, empty.x,empty.y, occupied.x,occupied.y)
  if empty.y ~= occupied.y or empty.x ~= occupied.x then
  Real_print('bb')
    if x == empty.x and y == empty.y then
    Real_print('cc')
      return true
    end
  end
  if x == occupied.x and y == occupied.y then
    Real_print('dd')
    return false
  end
  local curr = level[y][x]
  return curr ~= CELL_WALL and curr ~= CELL_CRATE and curr ~= CELL_CRATE_ON_TARGET
end

end
function dump_path(c)
  if c == nil then return end
  if not c.dir then
    assert(not c.moves)
    assert(not c.prev)
    io.stdout:write('\n')
    return
  end
  io.stdout:write('push '..c.dir..' ')
  local c2 = c.moves
  while c2 do
    if c2.dir then
      io.stdout:write('move '..c2.dir..' ')
    end
    c2 = c2.prev
  end
  dump_path(c.prev)