HELSINKI (Reuters) - A drop in the numbers of illegal migrants arriving on the Greek islands from Turkey shows that a deal struck between the European Union and Turkey to try to stem the flow is working, Turkish Prime Minister Ahmet Davutoglu said on Wednesday. Speaking during an official visit to Finland, Davutoglu said the number of illegal migrants arriving in Greece from Turkey had fallen to 350 in the last two days. (Reporting by Tuomas Forsell; Writing by David Dolan and Daren Butler; Editing by Nick Tattersall)