You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

what is the first event mentioned?, Context: The Russian Revolution is the series of revolutions in Russia in 1917, which destroyed the Tsarist autocracy and led to the creation of the Soviet Union. Following the abdication of Nicholas II of Russia, the Russian Provisional Government was established. In October 1917, a red faction revolution occurred in which the Red Guard, armed groups of workers and deserting soldiers directed by the Bolshevik Party, seized control of Saint Petersburg (then known as Petrograd) and began an immediate armed takeover of cities and villages throughout the former Russian Empire.
Solution: Russian Revolution
Why? This is a good example, and the Russian Revolution is the first event mentioned.

New input: What eastern bloc action was definted by a SInatra song?, Context: The six Warsaw Pact countries of Eastern Europe, while nominally independent, were widely recognized in the international community as the Soviet satellite states. All had been occupied by the Soviet Red Army in 1945, had Soviet-style socialist states imposed upon them, and had very restricted freedom of action in either domestic or international affairs. Any moves towards real independence were suppressed by military force – in the Hungarian Revolution of 1956 and the Prague Spring in 1968. Gorbachev abandoned the oppressive and expensive Brezhnev Doctrine, which mandated intervention in the Warsaw Pact states, in favor of non-intervention in the internal affairs of allies – jokingly termed the Sinatra Doctrine in a reference to the Frank Sinatra song "My Way".
Solution:
non-intervention