using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        var text = "+61410000000";

        var regex = new Regex(@"\+?\d{10,12}");

        regex.IsMatch(text).Dump();

        regex.IsMatch("614").Dump();

        regex.IsMatch("614000000").Dump();

        regex.IsMatch("0300000000").Dump();

        Console.WriteLine("Hello World");

    }

}