using System;

public class Program

{

    public static void Main()

    {

        Program p=new Program();

        int x=5;

        int y=4;

        int diff;

        var res= p.Sum(ref x,y,out diff);

        Console.WriteLine("ref value is "+x+"\n out value is "+diff);

    }

    public int Sum(ref int x,int y,out int diff)

    {

        diff=0;     

        diff=x-y;

        return x+y;

    }   

}