primeNumber

using System;
using System.Linq;

namespace UnweUpr2
{
    class Program
    {
        static void Main(string[] args)
        {
            int number;
            Console.WriteLine("Enter a random number to check if it's prime:");
            number = Convert.ToInt32(Console.ReadLine());

            int forCaseSt;
            Console.WriteLine("Choose an algorithm for checking the number (1 for SQRT, 2 for HALF).");
            forCaseSt = Convert.ToInt32(Console.ReadLine());


            if(forCaseSt == 1)
            {
                 double numberSqrt = Math.Sqrt(number);
                 int numberSqrtRound = (int)Math.Round(numberSqrt);

                 if (number == 0 || number == 1)
                 {
                     Console.WriteLine(number + " is not a prime number");
                 }
                 else
                 {
                     for (int i = 2; i <= numberSqrtRound; i++)
                     {
                         if (number % i == 0)
                         {
                             Console.WriteLine(number + " is not a prime number.");
                             return;
                         }
                     }
                     Console.WriteLine(number + " is a prime number.");
                 }
            }
            else if(forCaseSt == 2)
            {
                 double numberHalf = (double)(number / 2);
                 int numberHalfRound = (int)Math.Round(numberHalf);

                 if (number == 0 || number == 1)
                 {
                    Console.WriteLine(number + " is not a prime number");
                 }
                 else
                 {
                     for (int i = 2; i <= numberHalfRound; i++)
                     {
                         if (number % i == 0)
                         {
                             Console.WriteLine(number + " is not a prime number");
                             return;
                         }
                     }
                     Console.WriteLine(number + " is a prime number");
                 }
            }
        }
    }
}