Query 1s or sql for each Counterparty the minimum date when the amount of sales was maximum?

Question

SQL query optimization

It is required to write a query that returns for each Counterparty the minimum date when the sales amount was maximum, and the maximum date when the sales amount was minimum, as well as the sales amounts for these dates.
I’m wise for the second day. It’s not a problem to find a separately specified Counterparty. But for all counterparties, one request does not work. Everything was tested: JOIN, Subquery, Temporary tables, etc. Does not help.
At least I have an idea.