Prime numbers

    static void Main(string[] args)
    {
        List<int> numbers = ShowPrime();
        Int32.TryParse(Console.ReadLine(), out int count);
        List<string> limits = new List<string>();
        //считываем лимиты
        for (int i = 0; i < count; i++)
        {
            limits.Add(Console.ReadLine());
        }
        for (int i = 0; i < count; i++)
        {
            
            var limitgroup = limits[i].Split(' ');

            var start = numbers.FindLastIndex(x => x <= Int32.Parse(limitgroup[0]));
            var end = numbers.FindLastIndex(x => x <= Int32.Parse(limitgroup[1]));

            if (start < 0) start = 0;
            for (int j = start; j <= end; j++)
            {
                Console.WriteLine(numbers[j]);
            }
        }

    }

    public static List<int> ShowPrime()
    {
        List<int> numbers = new List<int>();
        bool isPrime;
        for (int i = 2; i <= 32000; i++)
        {
            isPrime = true;
            if (i > 10) { if (i % 10 == 5 || i % 2 == 0) continue; } // ускоритель
            for (int j = 2; j < (int)(Math.Sqrt(i) + 1); j++)
            {
                if (j * j - 1 > i) { isPrime = false; break; }
                if (i % j == 0 && i > 2) { isPrime = false; break; }
            }
            if (isPrime) numbers.Add(i);
        }

        return numbers;
    }

I get a wrong answear?but i check in list i have exatly only prime numbers? I dont understand which test is failed