Migrants wait on the Greek side of the border with Macedonia as a Macedonian policeman stands guard on the Macedonian side, near the Greek village of Idomeni, November 19, 2015. Balkan countries have begun filtering the flow of migrants to Europe, granting passage to those fleeing conflict in the Middle East and Afghanistan but turning back others from Africa and Asia, the United Nations and Reuters witnesses said on Thursday. REUTERS/Alexandros Avramidis