Shuck and clean corn; break corn in halves. Cut sausage into 2- to 3-inch pieces. Wash the potatoes; place them in a boiler full of water over medium-high heat in an 8-gallon pot or larger, half filled with water, place the package of crab and shrimp boil and seasoned salt in water. Bring the water to rolling boil; put in sausage and let them boil for 10 minutes. Remove the potatoes from their pot and place down in the pot with corn and sausage. Cook another 10 minutes. Wash the shrimp and add to the pot with the other. Sprinkle the Old Bay seasoning and cook for 2 minutes more. Cut off heat and allow the entire pot to sit for about 5 minutes. Serve with cocktail sauce and melted butter.