static void Main(string[] args)
{
Directory rootdir = new Directory("root");
Directory usrdir = new Directory("usr");
rootdir.Add(usrdir);
Directory yuki = new Directory("yuki");
usrdir.Add(yuki);
File file = new File("Composite.java", 100);
yuki.Add(file);
rootdir.PrintList();
Console.WriteLine("");
Console.WriteLine($"file = {file.GetFullName()}");
Console.WriteLine($"yuki = {yuki.GetFullName()}");
}