How to include one number instead of various number

I have below data set which has 3 columns in it.

My requirement is to get one number for “Bank Number” Column, if the Bank Name and Country name are same.

We can add any number into Bank Number column as below, but it should be one number for each line that contains the same Bank Name and Country.

Please help me with this guys. I have attached the Excel file for your reference.

Book1.xlsx

Thanks in advance.