using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.IO;

namespace ConsoleApplication1

{

    class Program

    {

        static void Main(string[] args)

        {

            StreamReader f = new StreamReader("C:\\Users\\elev\\Desktop\\ConsoleApplication3\\ConsoleApplication3\\unu.txt");

            StreamReader g = new StreamReader("C:\\Users\\elev\\Desktop\\ConsoleApplication3\\ConsoleApplication3\\doi.txt");

            StreamWriter h = new StreamWriter("C:\\Users\\elev\\Desktop\\ConsoleApplication3\\ConsoleApplication3\\trei.txt");

            int nr=0;

            string s;

            string[] c;

            c = new string[10];

            s=f.ReadLine();

            while(!f.EndOfStream)

            {

                c[++nr] = s;

                s=f.ReadLine();

            }

            c[++nr] = s;

            s=g.ReadLine();

            while(!g.EndOfStream)

            {

                c[++nr] = s;

                s=g.ReadLine();

            }

            c[++nr] = s;

            Array.Sort(c);

            for (int i = 1; i <= nr; i++)

            {

                h.WriteLine(c[i]);

            }

                h.Close();

        }

    }

}

​