Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_149426_4 (available_subnets INTEGER, network_mask VARCHAR)
### Question:
When the network mask is  255.255.255.128 what is the lowest available subnet?
### Answer:
SELECT MIN(available_subnets) FROM table_149426_4 WHERE network_mask = "255.255.255.128"