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

### Instruction:
What is the least amount of silver medals won by Total with more than 1 bronze and more than 18 total medals won?

### Inputs:
table_name: table, columns: ['Rank', 'Nation', 'Gold', 'Silver', 'Bronze', 'Total']

### Response:
SELECT MIN Silver FROM table WHERE Bronze > 1 AND Nation = total AND Total > 18