Two postmen meet on their routes and they start talking. Postman A says: "I know you have 3 sons, how old are they?" Postman B says: "If you take their ages in years, and multiply them together, the result is your age." A: "That's not enough info" B: "The sum of the 3 numbers equals the number of windows in that building over there." A: "Hmm... that's still not enough." B: "My middle son is red-haired." A: "Ah, now I see!" How old are the 3 sons?