Coding IF statements in Excel

I have created a Risk Log in Excel, there are two columns, labels Priority & Impact (where High (H), Medium (M) or Low (L) can be inputted). I would like to create a third column called "Measure". This will calculate a value based on the priority and the impact of these risks. The numbers are shown in the table below, where the horizontal axis is Impact, and the Vertical in Priority

 H  3   7   9
 M  2   5   8
 L  1   4   6
    L   M   H
Impact

So for example, a priority of H and an impact of H would give you 9 in the measure column, a priority of M and an impact of H would give you 8, and a priority of H and an impact of M would give you 7. I am not quite sure how to code the "Measure" column so that I get the number desired. I am assuming some kind of "If" statement, but not sure as there are so many options. Below is my current spreadsheet, and I would like to add the measure column to the right.

Any help is great! Thanks!