Find median in a stream, C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        /* Find median in a stream
           - List should be sorted.
           - if list size is base mdedian is (n+1)/2 th number
           - if list size is even , median is average of  n/2 number  and  (n+2)/2 number 
        */
        
        static int sum = 0;
        static int median = 0;
        //static Hashse hs = new Hashset();
        public static void Main(string[] args)
        {
           
            //Your code goes here
            Console.WriteLine("Hello, world!");
           SortedList lst = new SortedList();
           addNum(5, lst);
           addNum(15, lst);
           addNum(1, lst);
           addNum(3, lst);
           addNum(6, lst);
           addNum(8, lst);
            
        }
        public static void addNum(int n, SortedList lst) {            
            //Console.WriteLine(" The arr size  is " + lst.Count());
            lst.Add(n,n);
            int count = lst.Count;
            if( count % 2 == 0 ){
               int n1 = (int) lst.GetByIndex( (count/2) -1 ) ;
               int n2 =  (int) lst.GetByIndex((count + 2 )/2 - 1);
               Console.WriteLine(" The median is " + (n1 + n2 ) / 2 );
            } else {
                int n1 =0;
                if(count == 1)
                   n1= (int) lst.GetByIndex(0);
                else
                    n1= (int) lst.GetByIndex( (count + 1)/2 - 1) ;
                 Console.WriteLine(" The median is " + n1 );
            }
        }
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,37 sec, absolute running time: 0,41 sec, cpu time: 0,36 sec, average memory usage: 16 Mb, average nr of threads: 3, absolute service time: 0,82 sec