<prompt> Translate the following text to SwahiliThe sixth row, labeled Unknown shows some First-Class Mail that cannot be identified with any of the aforementioned four sectors.  <response>: Safu ya sita, iliyo na lebo Unknown inaonyesha baadhi ya barua ya darasa la kwanza ambayo haiwezi kutambuliwa na yoyote ya sekta nne zilizotajwa hapo juu. 