InDesign GREP reformatting of Time Ranges

Indesign GREP newbie here. I'm receiving text of times that requires reformating. How would I format time ranges using a GREP code to omit the first "am" or "pm" from any time ranges that have "am" or "pm" twice in the same time range? Also, I'm trying to omit the ":00" from all time ranges. Is there a simple way of eliminating that in the same GREP?

For Example:

This is what’s provided:

• 9:15am-10:00am

• 1:00pm-3:30pm

• 11:30am-12:30pm

• 9:00am-1:00pm

This is what I’m aiming for:

• 9:15-10am

• 1-3:30pm

• 11:30am-12:30pm

• 9am-1pm