Counting Unique Ticket Ids

I have a data which contains the number of customers who have logged cases with us to find a solution. So the data looks like as shown below;

Case IDCategoryCountrySubject QuestionClosing Details2550EMEADenmarkHi Please help me with the follwing orders, ticket number is JN567786Contact the retail shop12550EMEABelgiumHi please note that the product KA12QT seems to be having hardware problems. the ticket number is JN567786.

Technical issue fixed, DCK JN56778612876APJAustraliaProblem with the music system, resolution required.
The ticket Id logged is JN782238
new CD provided to resolve1

What i need to do is find out the unique ticket ID (eg: JN782238) from all the description provided from column 'Subject Question' and 'Closing Details'. All the ticket numbers start from JN... , however it is very manual for to check every row has a ticket number. I have to do this for many sheets and the data contains atleast 20 to 25000 lines.

Inorder to find this unique ticket number i search through filter by giving the criteria as JN1 and keep doing untill i reach JN9. Once i filter through each of these criteria, i add a number "1" in the last column indicating that this row contains a ticket number.

After completing for all the rows, I add a pivot to check the final count of the the unique numbers, But again i need to remove the duplicates from these count, as there might be several descriptions with the same ticket Id (eg:JN789899). So i add field "Case ID" to the row area in pivot and count of these numbers in the 'Value area' (pivot). Then i look for case IDs with numbers more than 1. I f i find 2 or 3 for a particular case Id then i search this case id in the data and delete one of the count ('1') in the last column.