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

### Instruction:
How many platforms have a southern opertator and the pattern is all stations via clapham junction?

### Inputs:
table_name: table, columns: ['Platform', 'Frequency (per hour)', 'Destination', 'Service Pattern', 'Operator', 'Line']

### Response:
SELECT COUNT Platform FROM table WHERE Operator = Southern AND Service Pattern = All stations via Clapham Junction