C# DateTime parse short string ("MMMyy")
===

I have a string which contains date and has a format of "MMMyy". How would it be possible to do that?  
Sample:  

    string date = "MAY09";
    DateTime a = DateTime.Parse("MAY09"); //Gives "2012.05.09 00:00:00"
    DateTime b = DateTime.ParseExact("MAY09", "MMMyy", null); //Gives error
    DateTime c = Convert.ToDateTime("MAY09"); //Gives "2012.05.09 00:00:00"
    
    I need "2009-05-01"