When the network mask is  255.255.255.128 what is the lowest available subnet?
CREATE TABLE "subnet_and_host_counts" (
  "prefix_size" text,
  "network_mask" text,
  "available_subnets" real,
  "usable_hosts_per_subnet" real,
  "total_usable_hosts" real
);
SELECT MIN("available_subnets") FROM "subnet_and_host_counts" WHERE "network_mask"='255.255.255.128';