Row count for DISTINCT over a GROUP BY aggregate

At an Avito interview they check whether the candidate understands that DISTINCT placed over the result of a grouping often changes nothing. Using the data in the events table, work out how many rows this query returns:

SELECT DISTINCT a, b, c, SUM(d) AS revenue
FROM events
GROUP BY a, b, c

Wrap this query and return the number of rows in a single column rows_returned.

Expected output sample

This is what a correct answer looks like — its row count is its own, it doesn't have to match the schema tables. Your answer must use the same column names as this sample — alias them with AS if needed.

rows_returned
11

Avito

Your query result will appear here

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