using System;

using System.Linq;

public class Program

{

    static void Main(string[] args)

        {

            Console.WriteLine(IsBetween10And20(5));

            Console.WriteLine(IsBetween10And20(15));

            /*

            False

            True

            */

​

​

            Console.WriteLine(AreAnagrams("Hello", "olleH"));

            Console.WriteLine(AreAnagrams("Hello", "olleh"));

            Console.WriteLine(AreAnagrams("Hello", "olleh", ignoreCase: true));

            Console.WriteLine(AreAnagrams("blue", "red"));

            /*

            True

            False

            True

            False

            */

        }

​

    static bool IsBetween10And20(int num)

    {

        return num >= 10 && num <= 20;

    }

​

    static bool AreAnagrams(string first, string second, bool ignoreCase = false)

    {

        if (first == second)

            return true;

        if ((first == null && second != null) || (second == null && first != null))

            return false;

        if (first!.Length != second!.Length)

            return false;

        if (ignoreCase)

        {

            first = first.ToLowerInvariant();

            second = second.ToLowerInvariant();

        }

​

        var firstSet = first.OrderBy(n => n).ToArray();

        var secondSet = second.OrderBy(n => n).ToArray();

        for (int i = 0; i < firstSet.Count(); i++)

            if (firstSet[i] != secondSet[i])

                return false;

​

        return true;

    }

}