SQL query

I am trying to get the data into blocks and then pick the 1st row in block if it is sale and pick the last row of the block if it is no sale. It will be similar kind of records for other people as well. This table has about 23,000 records.

CREATE TABLE test (Person VARCHAR(20),  Action VARCHAR(10), [Date]   DATE)
INSERT INTO test
VALUES      ('MAX','Sale','20100720'),
            ('MAX','Sale','20101026'),
            ('MAX','Sale','20101103'),
            ('MAX','Sale','20110401'),
            ('MAX','No Sale','20110528'),
            ('MAX','Sale','20110613'),
            ('MAX','Sale','20110711'),
            ('MAX','Sale','20110819'),
            ('MAX','No Sale','20111001'),
            ('MAX','No Sale','20111209'),
            ('MAX','Sale','20120201'),
            ('MAX','No Sale','20120201'),
            ('MAX','Sale','20120207'),
            ('MAX','Sale','20120213'),
            ('MAX','No Sale','20130706');
;with mycte as
                        (  
                        select *, row_number() Over(order By [Date],Action Desc) rn1
                        , row_number() Over(partition by  Action order By Date, aCTION desc) rn2 
                        , row_number() Over(order By [Date],Action DESC ) - row_number() Over(Partition by  Action Order By [Date] ) rn3 
                        from test)
        , mycte2 as 
                         ( Select *,row_number() Over(partition by  rn3 order By CASE WHEN Action='Sale'Then [Date] END, CASE WHEN Action='No Sale'Then [Date] END DESC) rn4
                         , row_number() Over(partition by Action,  rn3 order By Action  ) rn5 
                         from  mycte )
SELECT Person,Action,[Date],'Y' AS flag
        FROM   mycte2
        WHERE  rn4 = 1  OR rn5 = 1
        ORDER  BY [Date], ACTION DESC 
        
DROP TABLE test

/*
Person  Action  Date    flag
MAX     Sale    2010-07-20      Y
MAX     No Sale 2011-05-28      Y
MAX     Sale    2011-06-13      Y
MAX     No Sale 2011-12-09      Y
MAX     Sale    2012-02-01      Y
MAX     No Sale 2012-02-01      Y
MAX     Sale    2012-02-07      Y
MAX     No Sale 2013-07-06      Y

*/