class OS
{
    private static OS instance;
 
    public string Name { get; private set; }
    private static object syncRoot = new Object();
 
    protected OS(string name)
    {
        this.Name = name;
    }
 
    public static OS getInstance(string name)
    {
        if (instance == null)
        {
            lock (syncRoot)
            {
                if (instance == null)
                    instance = new OS(name);
            }
        }
        return instance;
    }
}