using System;

public class Program

{

    public static void Main()

    {

        Test("9", "10");

        Test("Hello World", "Hello world");

        Test("0000000000000", "1");

        Console.WriteLine();

​

        Test("", "");

        Test("123", "123");

        Test("aa123qwe000", "aa123qwe000");

        Console.WriteLine();

​

        Test("A", "");

        Test("Hello World0010", "Hello World9");

        Test("009", "1");

        Test("0000000000000", "000");

    }

    public static int Step = 0;

    public static void Test(string left, string right)

    {

        ++Step;

        var c = Compare(left, right);

        var r = c == 0

            ? "is equal to"

            : c < 0

            ? "is lesser than"

            : "is greater than";

​

        Console.WriteLine($"#{Step} '{left}' {r} '{right}'");

    }

    public static int Compare(string left, string right)

    {

        // Indexes

        var li = 0;

        var ri = 0;

​

        while (li < left.Length && ri < right.Length)

        {

            if (left[li] >= '0' && left[li] <= '9' && right[ri] >= '0' && right[ri] <= '9')

            {

                // Skip leading zeros

                if (left[li] == '0') ++li;

                if (right[ri] == '0') ++ri;

                while (li < left.Length && left[li] == '0') ++li;

                while (ri < right.Length && right[ri] == '0') ++ri;

​

                // Digits

                var ld = li;

                var rd = ri;

​

                // Consume significant digits

                while (li < left.Length && left[li] >= '0' && left[li] <= '9') ++li;

                while (ri < right.Length && right[ri] >= '0' && right[ri] <= '9') ++ri;

​

                // Magnitudes

                var lm = li - ld;

                var rm = ri - rd;

​

                if (lm < rm) return -1;

                if (lm > rm) return 1;

​

                while (ld < li)

                {

                    if (left[ld] < right[rd]) return -1;

                    if (left[ld] > right[rd]) return 1;

                    ++ld;

                    ++rd;

                }

​

                continue;

            }

​

            if (left[li] < right[ri]) return -1;

            if (left[li] > right[ri]) return 1;

            ++li;

            ++ri;

        }

​

        if (left.Length < right.Length) return -1;

        if (left.Length > right.Length) return 1;

        return 0;

    }

}