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

### Instruction:
What is the highest S ÷ D with a 2420 (220) [3H] paroxetine and an N ÷ D less than 393.8?

### Inputs:
table_name: table, columns: ['[ 3 H]CFT', '[ 3 H]Nisoxetine', '[ 3 H]Paroxetine', 'N ÷ D', 'S ÷ D']

### Response:
SELECT MAX S ÷ D FROM table WHERE [ 3 H]Paroxetine = 2420 (220) AND N ÷ D < 393.8