When the network mask is 255.255.255.128 what is the lowest available subnet?
CREATE TABLE table_19705 (
    "Prefix size" text,
    "Network mask" text,
    "Available subnets" real,
    "Usable hosts per subnet" real,
    "Total usable hosts" real
)
SELECT MIN("Available subnets") FROM table_19705 WHERE "Network mask" = '255.255.255.128'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: When the network mask is 255.255.255.128 what is the lowest available subnet? ### Input: CREATE TABLE table_19705 (
    "Prefix size" text,
    "Network mask" text,
    "Available subnets" real,
    "Usable hosts per subnet" real,
    "Total usable hosts" real
) ### Response: SELECT MIN("Available subnets") FROM table_19705 WHERE "Network mask" = '255.255.255.128'