Nested If's (I think)

I have 2 cols each require either a Y or N to be input into either col. How do I output a given value for each combination of Y or N. for e.g.
col 1 col 2 col 3 (value required)
y n = 1
n n = 2
y y = 3
n y = 3

I have tried to used a nested If with AND and OR function but no go, am I on the right track,
Please help have spent about 3 days playing with this.

Many thanks

Marco