using System;

public class Program

{

public static void PrintArray(int[] Array)

{

    int length = Array.Length;

    for (int i = length - 1; i >= 0; i--)

    {

        Console.Write(Array[i]);

​

    }

}

​

public static void SumDigitArrays(int[] a, int[] b, int[] result)

{

    int length = Math.Max(a.Length, b.Length);

    for (int i = 0; i < length; i++)

    {

        int lhs = (i < a.Length) ? a[i] : 0;

        int rhs = (i < b.Length) ? b[i] : 0;

​

        int sum = result[i] + lhs + rhs;

        result[i] = sum % 10;

​

        int carry = sum / 10; 

​

        if (i + 1 < result.Length)

        {

            result[i + 1] = result[i + 1] + carry;

        }

    }

}

public static void MultiplyDigitArrays(int[] lhs, int[] rhs, int[] result)

{        

     int length1 = Math.Max(lhs.Length, rhs.Length);

     for (int i = 0; i < length1; i++)

     {

        int[] PartialProduct = new int[result.Length];

​

        int length2 = Math.Min(lhs.Length, rhs.Length);

        for (int j = 0; j < length2; j++)

        {

            int multiplicand = (lhs.Length < rhs.Length) ? rhs[i] : lhs[i];

            int multiplier = (lhs.Length < rhs.Length) ? lhs[j] : rhs[j];

​

            int product = PartialProduct[i + j] + multiplicand * multiplier;

​

            PartialProduct[i + j] = product % 10;

            int carry = product / 10;

​

            PartialProduct[i + j + 1] = PartialProduct[i + j + 1] + carry;

        }

         var r = new int[result.Length];

         SumDigitArrays(PartialProduct, result, r);

         Array.Copy(r, 0, result, 0, result.Length);

    }

}

public static int[]  MultiplyDigitArrays(int[] lhs, int[] rhs)

    {

        int length1 = Math.Max(lhs.Length, rhs.Length);

        var result = new int[length1* length1];

​

        for (int i = 0; i < length1; i++)

        {

            int[] PartialProduct = new int[length1 * length1];

​

            int length2 = Math.Min(lhs.Length, rhs.Length);

            for (int j = 0; j < length2; j++)

            {

                int multiplicand = (lhs.Length < rhs.Length) ? rhs[i] : lhs[i];

                int multiplier = (lhs.Length < rhs.Length) ? lhs[j] : rhs[j];

​

                int product = PartialProduct[i + j] + multiplicand * multiplier;

​

                PartialProduct[i + j] = product % 10;

                int carry = product / 10;

​

                PartialProduct[i + j + 1] = PartialProduct[i + j + 1] + carry;

            }

            result = SumDigitArrays(PartialProduct, result);

        }

​

        return result;

    }

​

​

    public static int[] SumDigitArrays(int[] a, int[] b)

    {

        int length = Math.Max(a.Length, b.Length);

        var result = new int[length];

​

        for (int i = 0; i < length; i++)

        {

            int lhs = (i < a.Length) ? a[i] : 0;

            int rhs = (i < b.Length) ? b[i] : 0;

​

            int sum = result[i] + lhs + rhs;

            result[i] = sum % 10;

​

            int carry = sum / 10;

​

            if (i + 1 < result.Length)

            {

                result[i + 1] = result[i + 1] + carry;

            }

        }

​

        return result;

    }

    public static void Main()

    {

    int[] n1 = { 1, 1 };

    int[] n2 = { 1, 1 };

    int[] result = new int[Math.Max(n1.Length, n2.Length) * 2 + 1];

​

    result = MultiplyDigitArrays(n1, n2);

​

    PrintArray(result);

​

    Console.WriteLine();        

    }

}