Excel date lookup problem

I've got a simple table which I need to lookup the last date based on another columns criteria. For example:

A B C
Date Fed Spray
1 02/02/2004 n y
2 02/25/2004 y n
3 08/22/2005 n y
4 09/25/2006 y n


I want a cell to look at column b and return me the last date that there is a "y" in column b...in this case it would return 09/25/2006

If it was for column c it would return 08/22/2005