Count Total Number of Matching Cells Across Two Columns

Greetings,

I work in a call center and work with large spread sheets that sometimes contain more than 25,000 rows of information regarding individual phone interactions with clients. One column contains a time stamp from when a client's profile was created. The adjacent column contains a time stamp for the individual conversation. If the information in two adjacent cells matches, that indicates that the conversation was with a first-time caller. I need a formula that will count the number of times two adjacent cells within these two columns match one another.

If at all possible, I’d like to avoid an approach that requires creating another column, inserting a formula and dragging down to the final row. In the example workbook I’ve posted, there are 9 rows whose data is matching. A formula that could be placed in a single cell and calculate those nine instances would be excellent.

Thanks so much for your help.