#include <bits/stdc++.h>
using namespace std;
struct TreeNode {
	char val;
	TreeNode *left, *right;
};
int n;
char a, b, c, rootc;
TreeNode **nodes;
void preorder(TreeNode *root) {
	if (root == nullptr) return ;
	cout << root->val;
	preorder(root->left);
	preorder(root->right);
}
int main() {
	cin >> n;
	nodes = new TreeNode* [26];
	for (int i = 0; i < 26; i++) {
		nodes[i]->val = i + 'a';
		cout << "赋值完成！\n";
		nodes[i]->left = nodes[i]->right = nullptr;
		cout << "指针设置完成！\n";
		cout << "i = " << i << endl;
	}
	for (int i = 0; i < n; i++) {
		cin >> a >> b >> c;
		if (i == 0) rootc = a;
		if (b != '*') nodes[a - 'a']->left = nodes[b - 'a'];
		if (c != '*') nodes[a - 'a']->right = nodes[c - 'a'];
	}
	preorder(nodes[rootc - 'a']);
	delete[] nodes;
	return 0;
}