using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(IsVisaCard("4111111111111112"));

        Console.WriteLine(IsVisaCard("378282246310005"));

        Console.WriteLine(IsVisaCard("411111"));

    }

    public static bool IsVisaCard(string number) => Regex.Match(number, @"^4[0-9]{12}(?:[0-9]{3})?$").Success;

}