using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Numerics;
using System.Security.Cryptography;

namespace L5
{
    class Program
    {
        static void Main(string[] args)
        {
            //Job1();
            Job2();
        }

        private static void Job1()
        {
            Console.WriteLine("Job1");
            int p = 0, q = 0;
            int e = 65537;
            bool ok = true;

            while (ok)
            {
                p = (int)RandomIntegerBelow(100);
                ok = !IsPrime(p);
            }
            Console.WriteLine("P: "+p);

            ok = true;

            while (ok)
            {
                q = (int)RandomIntegerBelow(100);
                ok = !IsPrime(q);
            }
            Console.WriteLine("Q: "+q);

            int n = (p - 1) * (q - 1);
            int d = 0;
            for (int i = 1; i < 10000; i++)
            {
                if ((e * i) % n == 0)
                {
                    d = i;
                    break;
                }
            }

            Console.WriteLine("D: "+d);
        }

        private static void Job2()
        {
            int p = 0, q = 0, e = 0, d = 0;
            bool ok = true;

            while (ok)
            {
                p = (int)RandomIntegerBelow(100);
                ok = !IsPrime(p) || !IsPrime(2 * p + 1);
            }
            ok = true;
            Console.WriteLine("P: "+p);

            while (ok)
            {
                q = (int)RandomIntegerBelow(100);
                ok = !IsPrime(q) || !IsPrime(2 * q + 1);
            }
            ok = true;
            Console.WriteLine("Q: "+q);

            int n = (p - 1) * (q - 1);

            while (ok)
            {
                e = (int)RandomIntegerBelow(100);
                if (e % 2 == 1 && GCD(e, n) == 1)
                {
                    ok = false;
                }
            }
            Console.WriteLine("E: "+e);

            for (int i = 1; i < n * e; i++)
            {
                if (e * i % n == 0)
                {
                    d = i;
                    Console.WriteLine("D: " + d);
                    break;
                }
            }
        }

        private static bool IsPrime(int number)
        {
            if ((number & 1) == 0)
            {
                return (number == 2);
            }

            int limit = (int)Math.Sqrt(number);

            for (int i = 3; i <= limit; i += 2)
            {
                if ((number % i) == 0)
                {
                    return false;
                }
            }
            return true;
        }
        public static BigInteger RandomIntegerBelow(BigInteger N)
        {
            var rng = new RNGCryptoServiceProvider();
            byte[] bytes = N.ToByteArray();
            BigInteger R;

            do
            {
                rng.GetBytes(bytes);
                bytes[bytes.Length - 1] &= (byte)0x7F;
                R = new BigInteger(bytes);
            } while (R >= N);

            return R;
        }

        private static int GCD(int a, int b)
        {
            while (a != 0 && b != 0)
            {
                if (a > b)
                    a %= b;
                else
                    b %= a;
            }

            return a == 0 ? b : a;
        }
    }
}