When  гн(иј)ездо / gn(ij)ezdo is the serbo-croatian how many proto-slavics are there?
CREATE TABLE "selected_cognates" (
  "proto_slavic" text,
  "russian" text,
  "ukrainian" text,
  "belarusian" text,
  "polish" text,
  "czech" text,
  "slovak" text,
  "slovene" text,
  "serbo_croatian" text,
  "bulgarian" text,
  "macedonian" text
);
SELECT COUNT("proto_slavic") FROM "selected_cognates" WHERE "serbo_croatian"='гн(иј)ездо / gn(ij)ezdo';