View difference between Paste ID: hDsR9G9B and ugbYjTjP

 using System;
 using System.Collections.Generic;
 using System.Threading;
 
 class SieveOfEratosthenes
 {
     //Write a program that finds all prime numbers in the range [1...10 000 000]. Use the sieve of Eratosthenes algorithm (find it in Wikipedia).
 
     static void Main()
     {
         int endInterval = 10000000;
         bool[] sieve = new bool[endInterval];
 
         sieve[0] = true;
         sieve[1] = true;
 
         int lastCheck = (int)Math.Sqrt(sieve.Length);
 
         for (int index = 2; index <= lastCheck; index++)
         {
             if (!sieve[index])
             {
                 for (int j = index * index; j < sieve.Length; j += index)
                 {
                     sieve[j] = true;
                 }
             }
         }
 
         List<int> primesList = new List<int>();
 
         for (int index = 2; index < sieve.Length; index++)
         {
             if (!sieve[index])
             {
                 primesList.Add(index);
             }
         }
 
         Console.WriteLine(primesList.Count);//test: http://primes.utm.edu/howmany.shtml
         RithmOfPrimes(primesList);
-        RithmOfPrimes(primesList);
+
 
     private static void RithmOfPrimes(List<int> primesList)
     {
         int frequency = 440;
         int duration = 170;
 
-        int counter = primesList.Count;
+
         {
             Console.Clear();
             Thread.Sleep(duration + 1); //allows to hear full sound duration
             Console.WriteLine(prime);
 
             if (HasEvenDigitInLast2Digits(prime, ref frequency))
             {
-            if (HasEvenDigitInLast2Digits(prime))
+                Console.Beep(frequency, duration << 1);
             }
             else
             {
                 Console.Beep(frequency, duration);
             }
-                Console.Beep(frequency<<1, duration);
+
     }
 
     private static bool HasEvenDigitInLast2Digits(int prime, ref int frequency)
     {
-    private static bool HasEvenDigitInLast2Digits(int prime)
+
         int len = 2;
 
         while (count++ < len)
-        while (count++ < 2)
+
             int digit = prime % 10;
 
             if ((digit & 1) == 0 && digit != 0)
             {
                 frequency = SetFrequency(digit);
                 return true;
             }
 
             frequency = SetFrequency(digit);
             prime /= 10;
         }
 
         return false;
     }
 
     private static int SetFrequency(int digit)
     {
         int frequency = 0;
 
         switch (digit) //http://www.phy.mtu.edu/~suits/notefreqs.html
         {
             // sqrt is integer
             case 1:
             case 4:
             case 9: frequency = 392/*g4*/; break;
 
             //prime
             case 2:
             case 3:
             case 5:
             case 7: frequency = 494/*b4*/; break;
 
             //composite
             case 6:
             case 8: frequency = 440/*a4*/; break;
 
             //zero
             case 0: frequency = 294/*d4*/; break;
         }
         return frequency;
     }
 }