Teacher:Generate a correct and concise answer for the question based on the words in the context.
Teacher: Now, understand the problem? Solve this instance: Context : Production of the 2S5 Giatsint-S started in 1976 along with the towed version the 2A36 Giatsint-B. It was introduced into service in 1978 and has also been known as the M1981 by the United States.
Question : What was the year that 2S5 Giatsint-S entered service?
Student:
1978