A postman leaves the post office at 8:00 a.m. to deliver mail to the farm. On the road, you have to walk 12 kilometers uphill and 8 kilometers downhill. When going uphill, you walk 4 kilometers per hour, and when you go downhill, you walk 5 kilometers per hour. After arriving at the farm, you rest for 1 hour and return. Ask when the postman returns to the post office?
某邮递员早上8时从邮局出发，向农场送邮件．路上要走12公里的上坡路和8公里的下坡路，上坡时每小时走4公里，下坡时每小时走5公里，到农场后休息1小时开始返回．问邮递员什么时候返回邮局？
<result>6</result>