using System;

​

//pe VS merge

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Please provide a number");

        int primeNumber = int.Parse(Console.ReadLine());

         Prime third = new Prime(primeNumber, true);

            Console.WriteLine("The number {0} is prime: {1}",third.PrimeNUmber,third.IsItPrime);

            Console.WriteLine("Next prime is {0}",third.NextPrime());

    }

}

public class Prime

    {

        int primeNumber;

        bool isItPrime;

        public int PrimeNUmber { get { return primeNumber; } set { primeNumber = value; } }

​

        public bool IsItPrime

        {

            get { return isItPrime; }

            set

            {

                if (CheckPrime(PrimeNUmber))

                    isItPrime = true;

                else

                    isItPrime = false;

            }

        }

        public Prime(int primeNumber, bool isItPrime)

        {

            this.PrimeNUmber = primeNumber;

            this.IsItPrime = isItPrime;

        }

        private bool CheckPrime(int prime)

        {

            if (prime == 0 || prime == 1)

                return false;

            else if (prime <= 3)

                return true;

            else

            {

                for (int i = 2; i < Math.Sqrt(prime) + 1; i++)

                {

                    if (prime % i == 0)

                        return false;

                    if (i >= 3)

                        i++;

                }

                return true;

            }

        }

        public int NextPrime()

        {

            bool check = false;

            int container = PrimeNUmber;

            if (IsItPrime)

            {

                while (!check)

                {

                    if (container == 2)

                        container += 1;

                    else

                        container += 2;

                    check = CheckPrime(container);

                }

                return container;

            }

            else

            {

                while (!check)

                {

                    if (container <= 2)

                        container += 1;

                    else

                        container += 2;

                    check = CheckPrime(container);

                }

                return container;

            }

​

        }

    }