The performing the task corresponding to the first motion item may comprise, if the task corresponding to {TAIL ~ the first motion item} is channel changing from among the second tasks, changing a current channel to one of {HEAD ~ a previous channel} and a next channel of the current channel 
The performing the task corresponding to the first motion item may comprise , if the task corresponding to { TAIL ~ the first motion item } is channel changing from among the second tasks , changing a current channel to one of { HEAD ~ a previous channel } and a next channel of the current channel
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH