public class Program

{

   delegate string Collection(int a, int b);

   public void Main()

   {

      // Collection c;  // No methods attached to c

      // c = Multiply;  // Multiply attached to c

      // c += Subtract; // Multiply, Subtract attached to c

      // c -= Multiply; // Subtract attached to c

      Collection a = Multiply; // Multiply method attached to a

      a += Subtract;           // Multiply, Subtract methods attached to a

      Collection b = Divide;   // Divide method attached to b

      Collection c = a + b;    // Multiply, Subtract, Divide methods attached to c

   }

​

   string Multiply(int x, int y) 

   { 

       return (x * y).ToString(); 

   }

​

   string Subtract(int x, int y) 

   { 

       return (x - y).ToString(); 

   }    

​

   string Divide(int x, int y) 

   { 

       return (x / y).ToString(); 

   }        

}