static void Main(string[] args)
{
var leaf = new Leaf();
var mainTree = new Composite("main tree");
var subTree1 = new Composite("sub tree 1");
subTree1.Add(new Leaf());
subTree1.Add(new Leaf());
var subTree2 = new Composite("sub tree 2");
subTree2.Add(new Leaf());
mainTree.Add(subTree1);
mainTree.Add(subTree2);
mainTree.DoOperation();
}