Pity you didn't look a little further, where there was more syntax and semantics... The concept of a high-level language is, of course, relative, but if, for example, someone considers Forth to be an HLL, then imho, the language/formalism from the book about the Kiev machine was definitely one, and it was described in more detail by its chief architect, Katherine Yushchenko, in a book from 1963: https://it-history.lib.ru/TEXTS/Adresnoe-programmirovanie_EY...

If you are still interested, you can look at page 35, where there are several examples, including finding the GCD.