[Migrants wait for the distribution of aid at the camp in Idomeni, Greece, Monday, May 23, 2016. Thousands of stranded refugees and migrants have camped in Idomeni for months after the border was closed. (AP Photo/Darko Bandic)]ATHENS, Greece (AP) — Greek authorities say they will start a gradual evacuation of the country's main informal camp for refugees and other migrants within the next few days.