using System;

using System.Collections.Generic;

​

public class Program

{

    static int[] union(int[] id1, int[] id2)

        {

            int N1 = id1.Length;

            int N2 = id2.Length;

            int N = N1 + N2;            

            int k = 0;

            int[] _union = new int[N];            

            for (int i = 0; i < N1; i++)

            {

                _union[k++] = id1[i];                

            }

            for (int j = 0; j < id2.Length; j++)

            {

                bool isNonFound = true;

                for (int i = 0; i < N1; i++)

                {

                    if (id1[i] == id2[j])

                    {

                        isNonFound = false;

                        break;

                    }

                }

                if (isNonFound)

                    _union[k++] = id2[j];

            }

            if (k < N)

            {

                N = k;

                int[] _unionRes = new int[N];

                for (int i = 0; i < N; i++)

                    _unionRes[i] = _union[i];

                return _unionRes;

            }

            return _union;

        }

​

        static void inputArray(ref int[] arr, int N)

        {

            for (int i = 0; i < arr.Length; i++)

            {

                Console.WriteLine("Введите " + (i + 1) + "-элемент");

                arr[i] = Convert.ToInt32(Console.ReadLine());

            }

        }

​

        public static void Main(string[] args)

        {

​

            int N1, N2;

            int[] id1 = {1,2,3,4,5 };

            int[] id2 = {-1,1,1,2,3,6,7,8 };

​

            Console.WriteLine("Введите размер 1го множества:");

            N1 = Convert.ToInt32(Console.ReadLine());

            id1 = new int[N1];

            inputArray(ref id1, N1);

​

            Console.WriteLine("Введите размер 2го множества:");

            N2 = Convert.ToInt32(Console.ReadLine());

            id2 = new int[N2];

            inputArray(ref id2, N2);

​

​

            Console.WriteLine("Обьединение множеств:");

            IEnumerable<int> union12 = union(id1, id2);

​

            foreach (int id in union12)

                Console.WriteLine(id);

​

            //Console.WriteLine();

            //IEnumerable<int> bothR = id1.Union(id2);

​

            //foreach (int id in bothR)

            //    Console.WriteLine(id);

​

            Console.ReadKey();

        }

}