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

### Instruction:
When 318676 is the population of 2010 and 1st class is the income classification what is the area in kilometers squared?

### Inputs:
table_name: table, columns: ['City/Municipality', 'Population (2010)', 'Area (km²)', 'Pop. density (per km²)', 'Income Classification']

### Response:
SELECT Area (km²) FROM table WHERE Income Classification = 1st Class AND Population (2010) = 318676