In 1683, the Holy League of Austria, Poland, Venice, and  Russia was formed to oppose the Ottoman Empire. The Ottoman Empire suffered defeat at the Battle of Vienna in 1683 and was forced to withdraw rapidly from Central Europe. The defeat and the chaotic situation within the Ottoman Empire created widespread social disruption in the Central Balkans, particularly in the regions of Skopje and Niš, where Karposh's rebellion originated. On 25 October 1689, the Austrian branch of the Holy League, led by General Piccolomini, reached the Plain of Skopje and were met with rejoicing by the inhabitants of the villages there. The same day, Piccolomini began a withdrawal of his forces, and on October 26, set fire to the city. Skopje burned for two whole days, through the 26th and 27 October. Most of the city of Skopje was destroyed in the fire. Some accounts of these events state that Piccolomini razed Skopje due to an inability of his forces to occupy and govern a city so far from his headquarters, while other accounts state that it was perpetrated to prevent the spread of infectious disease.

Based on the above article, answer a question. How many countries consist of the Holy League?
4