#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <unordered_map>
#include <string>
using namespace std;


int main() {
	unordered_map<string, int> words;
	unordered_map<string, int> resWords;
	int cnt = 0;
	string word;
	while (true)
	{
		if (cin.peek() == '\n')
		{
			cnt ++;
			if (cnt == 2)
			{
				break;
			}
		}
		cin >> word;
		if (words.find(word) == words.end())
		{
			words.insert(make_pair(word, 1));
			resWords.insert(make_pair(word, 1));
		}
		else
		{
			words[word] ++;
			resWords[word] = 0;
		}
	}
	vector<string> results;
	for (auto i : words)
	{
		if (i.second == 1)
		{
			results.push_back(i.first);
		}
	}
	sort(results.begin(), results.end());
	for (int i = 0; i < results.size(); i++)
	{
		cout << results[i] << " ";
	}
	int x;
	cin >> x;
	return 0;
}