Stack Overflow Exception

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

namespace ConsoleApplication1
{

    class Program
    {
        int tries, numbersmatched, sel1, sel2, sel3, sel4, sel5, sel6, num1, num2, num3, num4, num5, num6;
        Random random = new Random();
        

        public void Menu()
        {
                LotteryNumbers();
                UserNumbers();
                Console.WriteLine("Lottery numbers: {0}, {1}, {2}, {3}, {4}, {5}", num1, num2, num3, num4, num5, num6);
                Console.WriteLine("Your numbers: {0}, {1}, {2}, {3}, {4}, {5}", sel1, sel2, sel3, sel4, sel5, sel6);
                CheckWin();
                Console.WriteLine("You matched " + numbersmatched + " numbers.");
                tries++;
                Menu();
        }

        public void UserNumbers()
        {
            sel1 = random.Next(1, 49);
            sel2 = random.Next(1, 49);
            while (sel1 == sel2)
            {
                sel2 = random.Next(1, 49);
            }
            sel3 = random.Next(1, 49);
            while (sel1 == sel3 || sel2 == sel3)
            {
                sel3 = random.Next(1, 49);
            }
            sel4 = random.Next(1, 49);
            while (sel1 == sel4 || sel2 == sel4 || sel3 == sel4)
            {
                sel4 = random.Next(1, 49);
            }
            sel5 = random.Next(1, 49);
            while (sel1 == sel5 || sel2 == sel5 || sel3 == sel5 || sel4 == sel5)
            {
                sel5 = random.Next(1, 49);
            }
            sel6 = random.Next(1, 49);
            while (sel1 == sel6 || sel2 == sel6 || sel3 == sel6 || sel4 == sel6 || sel5 == sel6)
            {
                sel6 = random.Next(1, 49);
            }
        }

        public void LotteryNumbers()
        {
            num1 = random.Next(1, 49);
            num2 = random.Next(1, 49);
            while (num1 == num2)
            {
                num2 = random.Next(1, 49);
            }
            num3 = random.Next(1, 49);
            while (num1 == num3 || num2 == num3)
            {
                num3 = random.Next(1, 49);
            }
            num4 = random.Next(1, 49);
            while (num1 == num4 || num2 == num4 || num3 == num4)
            {
                num4 = random.Next(1, 49);
            }
            num5 = random.Next(1, 49);
            while (num1 == num5 || num2 == num5 || num3 == num5 || num4 == num5)
            {
                num5 = random.Next(1, 49);
            }
            num6 = random.Next(1, 49);
            while (num1 == num6 || num2 == num6 || num3 == num6 || num4 == num6 || num5 == num6)
            {
                num6 = random.Next(1, 49);
            }
        }

        public void CheckWin()
        {
            numbersmatched = 0;
            if (sel1 == num1 || sel1 == num2 || sel1 == num3 || sel1 == num4 || sel1 == num5 || sel1 == num6)
            {
                numbersmatched++;
            }
            if (sel2 == num1 || sel2 == num2 || sel2 == num3 || sel2 == num4 || sel2 == num5 || sel2 == num6)
            {
                numbersmatched++;
            }
            if (sel3 == num1 || sel3 == num2 || sel3 == num3 || sel3 == num4 || sel3 == num5 || sel3 == num6)
            {
                numbersmatched++;
            }
            if (sel4 == num1 || sel4 == num2 || sel4 == num3 || sel4 == num4 || sel4 == num5 || sel4 == num6)
            {
                numbersmatched++;
            }
            if (sel5 == num1 || sel5 == num2 || sel5 == num3 || sel5 == num4 || sel5 == num5 || sel5 == num6)
            {
                numbersmatched++;
            }
            if (sel6 == num1 || sel6 == num2 || sel6 == num3 || sel6 == num4 || sel6 == num5 || sel6 == num6)
            {
                numbersmatched++;
            }
        }
        static void Main(string[] args)
        {
            Program Lottery = new Program();
            Lottery.tries = 0;
            Lottery.Menu();
        }


    }

}