I have a flight booked from Kiev to Amsterdam by way of Riga. Coincidentally, I may have to go to Latvia for a few days before the date of the flight. It would save me a good deal of trouble not to have to go all the way back to Ukraine just to turn around and fly back. Would it pose any problem to only fly the second leg of the journey, from Riga to Amsterdam? Is this something I'd need to communicate with the airline about? Would they, for instance, notice I hadn't taken the first leg and cancel the second one?