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

### Instruction:
What is the total number of acres at Sai Tso Wan, opening before 1978?

### Inputs:
table_name: table, columns: ['Landfill', 'Location', 'Acres', 'Opened', 'Capacity', 'Status', 'Rehab Period']

### Response:
SELECT COUNT Acres FROM table WHERE Landfill = sai tso wan AND Opened < 1978