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 (total_usable_hosts INTEGER, network_mask VARCHAR)
### Question:
When the network mask is 255.255.255.224 what is the highest  total usable host?
### Answer:
SELECT MAX(total_usable_hosts) FROM table_149426_4 WHERE network_mask = "255.255.255.224"