Answer:
The Congress of Berlin, held from June 13th to July 13th, 1878, was a meeting of leaders of the great European powers and the Ottoman Empire in Berlin in 1878. Following the Russian-Turkish War of 1877-1878, the objective of the meeting was to reorganize the Balkan countries. Otto von Bismarck, who led Congress, pledged to balance the different interests of Britain, Russia and Austria-Hungary. As a consequence, however, intensified the differences between Russia and Austria-Hungary, and the Balkan nationality issues.
The congress aimed at revising the Treaty of San Stefano and keeping Constantinople in Ottoman hands. The Congress of Berlin redistributed back to the Ottoman Empire certain Bulgarian territories which the earlier treaty had given to the Principality of Bulgaria, most notably to Macedonia.