Detailed Instructions: Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.
Q: Context: In a brief period between World War I and World War II the Kingdom of Yugoslavia, successor to the Kingdom of Serbia, formed a ''Small Entente'' loose union between Czechoslovakia, Romania and Yugoslavia. 
 Question: Which replaced the Kingdom of Serbia?
A:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
kingdom of yugoslavia