Field value = A. If A is blank, B. If A&B are blank, C

Field value = A. If A is blank, B. If A&B are blank, C

I have 4 fields.  I want the "Result" field to display the value of either A, or B, or C, depending on which fields are EMPTY.  If A is not empty, Result field value is A. If A is empty, result is B. If A & B are empty, show C. If A B C are empty then blank. For example, if B is the only empty field then it would still show A.
  1. Field A
  2. Field B
  3. Field C
  4. Field Result
I know how to do something like this in Excel, but can this be done within ZohoCRM?