森林转化二叉树。输入森林中各树的广义表，建立森林，并将其转化为二叉树，输出森林中各树的先序遍历结果以及转化后的二叉树先序遍历结果-Convert forest to binary tree. Input generalized lists of each tree in a forest, establish this forest, and convert it to a binary tree. Output preorder traversal results of each tree in the forest and the transformed binary tree.