Tens of thousands of migrants, mainly from the Middle East and Africa, use the Balkans route to get into the European Union, passing from Greece to Macedonia and Serbia and then to western Europe. After walking across the border into Macedonia to the small local station of Gevgelia, migrants pile onto an overcrowded four-carriage train in sweltering heat, young infants among them, to travel about 200 km north. Their aim: to enter Serbia on foot, another step in their uncertain search for a better life.