Count pairs of values in adjacent columns (either way around)

I have pairs of values in adjacent columns. I should like a count of the number of times each pair occurs - either way around, i.e. Mary-Fred OR Fred-Mary. Thx. Example:

Bill Joe 1
Sue Mary 1
Fred Mary 2
Joe Sue 1
Mary Fred 2

C1

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Try this and copy towards down
Change the range as per your needs

Or
=sumproduct(countifs(a$1:a$5,a1:b1,b$1:b$5,choose({1,2},b1,a1)))