using System;

using UnitsNet;

​

public class Program

{

    public static void Main()

    {

        double onePoundInKg = 0.45;

        double twoPoundsInKg = 0.90;

        Console.WriteLine(Mass.FromKilograms(onePoundInKg - twoPoundsInKg).StonePounds.ToString());

    }

}