A man holding a Greek flag shouts slogans during a rally in front of the White Tower, a landmark of the northern Greek city of Thessaloniki, Friday, Dec. 14, 2018. Hundreds of people protest against government efforts to end a three-decade-old dispute with neighboring Macedonia as the Greek Prime Minister Alexis Tsipras will deliver a speech to party cadres and supporters. (AP Photo/Giannis Papanikos)

A woman holding a religious icon shouts slogans in front of riot police during a rally in the northern Greek city of Thessaloniki, Friday, Dec. 14, 2018. Hundreds of people protest against government efforts to end a three-decade-old dispute with neighboring Macedonia as the Greek Prime Minister Alexis Tsipras will deliver a speech to party cadres and supporters. (AP Photo/Giannis Papanikos)

Hooded protesters gesture in front of riot police during a rally in the northern Greek city of Thessaloniki, Friday, Dec. 14, 2018. Hundreds of people protest against government efforts to end a three-decade-old dispute with neighboring Macedonia as the Greek Prime Minister Alexis Tsipras will deliver a speech to party cadres and supporters. (AP Photo/Giannis Papanikos)

Riot police take cover as protesters throw fireworks during a rally in the northern Greek city of Thessaloniki, Friday, Dec. 14, 2018. Hundreds of people protest against government efforts to end a three-decade-old dispute with neighboring Macedonia as the Greek Prime Minister Alexis Tsipras delivered a speech to party cadres and supporters. (AP Photo/Giannis Papanikos)