Most Free Time

/*************************************************************************
*                                                                        *
*  Using the JavaScript language, have the function MostFreeTime(strArr) *
*  read the strArr parameter being passed which will represent a full    *
*  day and will be filled with events that span from time X to time Y in *
*  the day. The format of each event will be hh:mmAM/PM-hh:mmAM/PM.      *
*  For example, strArr may be                                            *
*  ["10:00AM-12:30PM","02:00PM-02:45PM","09:10AM-09:50AM"]. Your program *
*  will have to output the longest amount of free time available         *
*  between the start of your first event and the end of your last event  *
*  in the format: hh:mm. The start event should be the earliest event    *
*  in the day and the latest event should be the latest event in the     *
*  day. The output for the previous input would therefore be 01:30       *
*  (with the earliest event in the day starting at 09:10AM and the       *
*  latest event ending at 02:45PM). The input will contain at least 3    *
*  events and the events may be out of order.                            *
*                                                                        *
*************************************************************************/
function MostFreeTime(strArr) { 

  // code goes here  
  return strArr; 
         
}

//"12:15PM-02:00PM","09:00AM-10:00AM","10:30AM-12:00PM"  -->  "00:30"
//"12:15PM-02:00PM","09:00AM-12:11PM","02:02PM-04:00PM"  -->  "00:04"