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

### Instruction:
Which best 3-year period has a best 15-year period of smyslov; kasparov, and a Position of 5?

### Inputs:
table_name: table, columns: ['Position', 'best year', 'best 2-year period', 'best 3-year period', 'best 5-year period', 'best 10-year period', 'best 15-year period']

### Response:
SELECT best 3-year period FROM table WHERE best 15-year period = smyslov; kasparov AND Position = 5