using System;

public class Program

{

    public static void Main()

    {

        ///-------------------------------

        //Add();

        int a;

        int b;

        a = 10;

        b = 20;

        DisplaySum(a,b);

        // 10 and 20 are int constants 

        DisplaySum(10,20);

        DisplaySum(30,b);

        DisplaySum(b,90);

        //--------------------------------------------

    }

    public static void DisplaySum(int a, int b)

    {

        //int c = a + b;

        int c;

        c = a + b;  

        Console.WriteLine( "Sum of " + a + " and " +  b + " is " + c );

    }

    public static void Add()

    {

        int a;

        int b;

        a = 10;

        b = 20;

        //int c = a + b;

        int c;

        c = a + b;

        Console.WriteLine( "Sum of a and b is " + c );

    }

}