Generate a correct and concise answer for the question based on the words in the context.
One example: Context : Isaac Nicola Romero (1916 in Havana, Cuba -- 1997) was a prominent Cuban guitarist and one of the founders of the modern Cuban Guitar School. 
Question : What was Isaac Nicola's city of birth?
Solution is here: Havana
Explanation: According to context Issac Nicola's city of birth is Havana. Hence this is a correct output.

Now, solve this: Context : The Buk-1 was adopted into service in 1978 following completion of state trials, while the complete Buk missile system was accepted into service in 1980 after state trials took place between 1977 and 1979. 
Question : Which was the official year for the approval of Buk missile system?
Solution:
1979