уже лучше

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

namespace SYATP2
{   class GoingBeyondTheSetException : Exception
    {
        public GoingBeyondTheSetException()
        {
            Console.WriteLine("Выход за пределы множества");
        }
    }

    abstract class Set
    {   public abstract int Maxi { get; set; }

        public abstract void AddItem(ref int item);
        public abstract void DeleteItem(ref int item);
        public abstract bool CheckItem(ref int item);
        public void Fill(string s)
        {
            //Console.WriteLine("Введите строку с элементами множества");
            //string buf = Console.ReadLine();
            int[] a = s.Split(' ').Select(x => int.Parse(x)).ToArray();
            for (int i = 0; i < a.Length; i++)
            {  if (a[i] > Maxi) throw new GoingBeyondTheSetException();
                AddItem(ref a[i]);
            }
        }

        public  void Fill(int [] a)
        {
            for (int i = 0; i < a.Length; i++)
            {
                if (a[i] > Maxi) throw new GoingBeyondTheSetException();
                AddItem(ref a[i]);
            }

        }
        public void Show()
        {
            for (int i =1 ; i <= Maxi; i++)
            {
                if (CheckItem(ref i)) Console.Write(i+" ");

            }

        }

    }
    class SimpleSet :Set
    {
        int maxi;
        bool[] simpleset;
        public override int Maxi
        {
            get { return maxi; }
            set { maxi = value; }

        }
        public override void AddItem(ref int item)
        {
            if (item > maxi) throw new GoingBeyondTheSetException();
            simpleset[item] = true;
        }
        public override void DeleteItem(ref int item)
        {
            simpleset[item] = false;
        }
        public override bool CheckItem(ref int item)
        {
            return (simpleset[item]);
        }
        public SimpleSet(int maxi)
        {
            Maxi = maxi;
            simpleset = new bool[maxi+1];
        }
        public static SimpleSet operator +(SimpleSet a, SimpleSet b)
        {
            int maxi;
            if (a.maxi > b.maxi) maxi = a.maxi;
            else maxi = b.maxi;
            SimpleSet c = new SimpleSet(maxi);
            for (int i = 1; i <= a.maxi; i++)
            {
                if (a.simpleset[i] == true)
                    c.simpleset[i] = true;
            }
            for (int i = 1; i <= b.maxi; i++)
            {
                if (b.simpleset[i] == true)
                    c.simpleset[i] = true;
            }
            return c;
        }
        public static SimpleSet operator *(SimpleSet a, SimpleSet b)
        {
            int maxi;
            if (a.maxi > b.maxi) maxi = b.maxi;
            else maxi = a.maxi;
            SimpleSet c = new SimpleSet(maxi);
            for (int i = 1; i <= maxi; i++)
            {
                if (a.simpleset[i] == true && b.simpleset[i]==true)
                    c.simpleset[i] = true;
            }

            return c;
        }
    }
   class BitSet : Set
    {
        int maxi;
        int[] bitset;
      //  int[] mask_= { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 };
        string mask = "";
        public override int Maxi
        {
            get { return maxi; }
            set { maxi = value; }

        }
        public string BitString(int idx)
        {
            string s = bitset[idx].ToString();
            string item ="";
           // var l = new List<int>();
            for (int i = 0; i < 32; i++)
            {    if (i < s.Length)
                    item += s[i];
                else item += "0";

            }
            item = new string(s.Reverse().ToArray());

            return item;
        }
        public void Offset(int idx)
        {
            for (int i = 31; i >= 0; i--)
            {   if (i == idx)
                    mask += "1";
                else mask += "0";
            }
           // mask = new string(mask.Reverse().ToArray());
        }
        public override void AddItem(ref int a)
        {

            int idx = a / 32;
            string item = BitString(idx);
            int n = a % 32;
            Offset(n);
            int a1 = Convert.ToInt32(item, 2);
            int a2 =  Convert.ToInt32(mask, 2);
            int res = (a1 | a2);
            string result = Convert.ToString(res, 2);
             while (result.Length != 32) result = "0" + result;
            Console.WriteLine(result);

            mask = "";

        }
        public override void DeleteItem(ref int a)
        {
            return;

        }
        public override bool CheckItem(ref int a)
        {
            return false;
        }
        public BitSet(int maxi)
        {
            Maxi = maxi;
            bitset = new int[maxi + 1];
        }
       /* public static BitSet operator +(BitSet a, BitSet b)
        {
           int maxi;
            if (a.maxi > b.maxi) maxi = a.maxi;
            else maxi = b.maxi;
            BitSet c = new BitSet(maxi);
            for (int i = 1; i <= a.maxi; i++)
            {
                if (a.bitset[i] == true)
                    c.bitset[i] = true;
            }
            for (int i = 1; i <= b.maxi; i++)
            {
                if (b.bitset[i] == true)
                    c.bitset[i] = true;
            }
            return c;
        }
        public static BitSet operator *(BitSet a, BitSet b)
        {
            int maxi;
            if (a.maxi > b.maxi) maxi = b.maxi;
            else maxi = a.maxi;
            SimpleSet c = new SimpleSet(maxi);
            for (int i = 1; i <= maxi; i++)
            {
                if (a.bitset[i] == true && b.bitset[i] == true)
                    c.bitset[i] = true;
            }

            return c;
        }*/

    }
    class MultiSet : Set
    {
        int maxi;
        int[] multiset;
        public override int Maxi
        {
            get { return maxi; }
            set { maxi = value; }

        }
        public override void AddItem(ref int item)
        {
            if (item > maxi) throw new GoingBeyondTheSetException();
            multiset[item]++;
        }
        public override void DeleteItem(ref int item)
        { if (multiset[item]!=0) multiset[item]--;

        }
        public override bool CheckItem(ref int item)
        {
            return (multiset[item] > 0);
        }
        public MultiSet(int maxi)
        {
            Maxi = maxi;
            multiset = new int[maxi + 1];
        }

    }
    class Program
    {   static void NewSet(Set s)
        {

            int a = 2;
            s.AddItem(ref a);
            a = 5;
            s.AddItem(ref a);
            a = 10;
            s.AddItem(ref a);
            s.Show();

        }
       /* static void Test()
        {
            Console.WriteLine("Введите первое множество");
            buf = Console.ReadLine();
            x = double.Parse(buf);
            ok = true;
        }*/
        static void Main(string[] args)
        {
            SimpleSet s = new SimpleSet(10);
            NewSet(s);
            BitSet b = new BitSet(10);
            int a = 5;
            b.AddItem(ref a);
        }
    }
}