CREATE TABLE table_26757_4 (proto_slavic VARCHAR, serbo_croatian VARCHAR)
When  гн(иј)ездо / gn(ij)ezdo is the serbo-croatian how many proto-slavics are there?
SELECT COUNT(proto_slavic) FROM table_26757_4 WHERE serbo_croatian = "гн(иј)ездо / gn(ij)ezdo"