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

### Instruction:
What is the highest Laps, when Bike is "Yamaha YZF-R1", when Rider is "David Checa", and when Grid is greater than 18?

### Inputs:
table_name: table, columns: ['Rider', 'Bike', 'Laps', 'Time', 'Grid']

### Response:
SELECT MAX Laps FROM table WHERE Bike = yamaha yzf-r1 AND Rider = david checa AND Grid > 18