Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What's the series number of the episode with season number 2?

### Inputs:
table_name: table, columns: ['Series No.', 'Season No.', 'Title', 'Directed by', 'Written by', 'Original air date', 'U.K. viewers (million)']

### Response:
SELECT MIN Series No. FROM table WHERE Season No. = 2