In Bulgaria, you can exchange RUB for BGN (left), but at a bad exchange rate. You can withdraw from any Russian card the left in the ATM. Or go straight from EUR.

In Bulgaria, rubles, as an inconvertible currency, change to the left not in all banks. In any case, if you find a bank engaged in such an exchange, it will be a three-fold: rubles -> EUR -> left. And, as a result, it will be much less profitable than if in Russia to exchange rubles for EUR and enter Bulgaria with euros.

In addition to banks, of course, you can find exchangers working with rubles (especially in resort areas), and also change at airports, but the profitability of the course in this case is out of the question. If the option of buying EUR in Russia is not good for some reason, it would be more convenient not to carry cash rubles to the country, but take with you a ruble bank card, in which to take left in Bulgaria or pay directly (for example, in supermarkets) .

There is also a third option - to try to exchange rubles not in official exchangers, but in exchangers with casinos or pawnshops, gold trading companies - however, it's difficult to judge the "correctness" of the course in this case.