using System;

using System.Globalization;

​

public class Program

{

    public static void Main()

    {

        CompareInfo info = CultureInfo.CurrentCulture.CompareInfo;

        string str = "منّم";

        Console.WriteLine(info.IndexOf(str, "من", CompareOptions.OrdinalIgnoreCase));

        Console.WriteLine("Done!");

        Console.ReadLine();

    }

}