C-sharp: Convert

Convert.cs

 int n;
            n = int.Parse(Console.ReadLine());
            double sum = 0.0;
            for (int iCount = 1; iCount <= n; iCount++)
            {
                sum = sum + 1 / iCount;
            }
            Console.WriteLine("Ket qua: {0}", sum);


            int n;
            n = int.Parse(Console.ReadLine());
            double sum = 0.0;
            for (int iCount = 1; iCount <= n; iCount++)
            {
                sum = sum + 1 / Convert.ToDouble(iCount);
            }
            Console.WriteLine("Ket qua: {0}", sum);


            int n;
            n = int.Parse(Console.ReadLine());
            double sum = 0.0;
            for (int iCount = 1; iCount <= n; iCount++)
            {
                sum = sum + 1.0 / iCount;
            }
            Console.WriteLine("Ket qua: {0}", sum);