using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(ValidatePin("1234"));

        Console.WriteLine(ValidatePin("12345"));

        Console.WriteLine(ValidatePin("a234"));

    }

    public static bool ValidatePin(string pin)

    {

​

       //below condition will return true if length is 4 or 6, otherwise false

       var condition = (pin.Length == 4 || pin.Length == 6) && int.TryParse(pin, out int pinn);

       return condition;

    }

}