using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            c1 c;
            c2 cc  = new c2();
            c2 ccc = new c2(10);

            Console.WriteLine(cc.v);
            Console.WriteLine(ccc.v);

        }
        class c1
        {
            public int v;
            public c1()
            {
                v = 0;
            }
            public c1(int x)
            {
                v = x;
            }
        }
        class c2 : c1
        {

        }
    }
}