Help with tricky function

I have a set of data in which I am trying to analyze and filter thru some information and not sure of the best way to get started. I apologize I am pretty good at using excel for formatting, etc. but when it comes to functions I am no expert. Basically I want to flag column A if all of column B for a given column A is CLS. This is just a start to the 50,000 rows of data I am looking thru. So out of the data below I want to somehow "flag" column A where column A equals 1006, 1010 and 1015 because all of their column B values are CLS. If this makes no sense I will try to explain better. Please help me at least get going in the right direction. Thank you!

Col A Col B
1005 ACT
1005 ACT
1005 ACT
1005 ACT
1006 CLS
1006 CLS
1006 CLS
1006 CLS
1006 CLS
1006 CLS
1006 CLS
1007 ACT
1007 ACT
1009 ACT
1009 ACT
1009 ACT
1010 CLS
1011 ACT
1011 ACT
1011 ACT
1013 CLS
1013 ACT
1015 CLS
1015 CLS
1015 CLS
1017 ACT
1017 ACT
1017 ACT
1017 ACT
1017 ACT
1017 ACT

Hi,

Welcome to the forum, but......

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deleted
mod came swooping in lol