#include <iostream>
#include <string>

using namespace std;

struct TreeItem {
	TreeItem* left;
	TreeItem* right;
	string data;
	TreeItem(){
		left = NULL;
		right = NULL;
	}
};

void treeWalk(TreeItem* item){
	if(item == NULL) return;
	treeWalk(item->left);
	treeWalk(item->right);
	cout << item->data << endl;
}

int main(){
	TreeItem* root;
	TreeItem* cur;

	root = new TreeItem();
	root->data = "data0";

	cur = new TreeItem();
	cur->data = "data1";
	root->left = cur;

	cur = new TreeItem();
	cur->data = "data2";
	root->right = cur;

	cur = new TreeItem();
	cur->data = "data3";
	root->right->left = cur;

	cur = new TreeItem();
	cur->data = "data4";
	root->right->right = cur;

	treeWalk(root);
}