NZEC in C#

[mayundo]

I keep getting nzec error. It's frustrating. What is wrong with the following code?

using System;

namespace ConsoleApplication1
{
class Program
{
static string Multiply(string String1, string String2)
{
const int size = 9;
int temp = String1.Length % size == 0 ? 0 : 1;
int size1 = String1.Length / size + temp;
temp = String2.Length % size == 0 ? 0 : 1;
int size2 = String2.Length / size + temp;
int psize = size1 + size2 - 1;
ulong[] number1 = new ulong[size1];
ulong[] number2 = new ulong[size2];
ulong[] product = new ulong[psize];

        int i=0;
        for (; i < size1 - 1; i++)
            number1[i] = ulong.Parse(String1.Substring(i * size, size));
        number1[i] = ulong.Parse(String1.Substring(i * size));

        for (i = 0; i < size2 - 1; i++)
            number2[i] = ulong.Parse(String2.Substring(i * size, size));
        number2[i] = ulong.Parse(String2.Substring(i * size));

        for (i = 0; i < size1; i++)
        {
            for (int j = 0; j < size2; j++)
            {
                product[i + j] += number1[i] * number2[j];
            }
        }

        string result = "";
        foreach (ulong u in product)
            result += u;

        return result.TrimStart('0');
    }

    static int Main(string[] args)
    {
        int count = int.Parse(Console.ReadLine());
        string Num1, Num2, Res = "";

        while (count-- > 0)
        {
            Num1 = Console.ReadLine();
            Num2 = Console.ReadLine();
            Res = Multiply(Num1, Num2);
            if (Res == "")
                Res = "0";
            Console.WriteLine(Res);
        }

        return 0;
    }
}

}

[leppyr64]

Which problem are you working on? A link will be sufficient.

Please post your code using the code tags (see the button above the window you post in).

[leppyr64]

Are you testing your code at all? It won't even pass the sample test case.

Your biggest problem at this time is that Console.ReadLine() reads the entire line.
In your first iteration using the sample test case, num1 will be "4 2" and num2 will be "123 43".