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

### Instruction:
What is the total number of Viewers with a Rank (Night) of n/a, and a Timeslot of 8:30 p.m.?

### Inputs:
table_name: table, columns: ['Episode', 'Air Date', 'Timeslot', 'Rating', 'Share', '18-49 (Rating/Share)', 'Viewers (m)', 'Rank (Timeslot)', 'Rank (Night)', 'Rank (Overall)']

### Response:
SELECT COUNT Viewers (m) FROM table WHERE Rank (Night) = n/a AND Timeslot = 8:30 p.m.