need help with a formula

[Tamana6147]

I need help creating a formula in excel within a pivot Table. 

For example, I am analyzing Column A, B and C. each of the columns contain Items 1, 2, 3 and so on. 

I need a formula for my a pivot table in which I state that all items that were already listed in Column A and are also in Column B should not be included. I only need to list only the items that are significant to just Column B itself--not including the same ones listed in both columns A and B- Hope that makes sense. PLEASE HELP. 

[#2]

I suggest adding a column in the source data that uses a formula to count each single cell in column C in column B, such as the following:

=Countifs(B:B,C2)

This will return how many times the value in C2 appears in column B, then drag the formula in the whole new column.

After that, use the new column in the Pivot Table filter section and select only the 0 values.