#include <fstream>
#include <set>

using namespace std;

int main(void)
{
	set<int> array;
	ifstream fin("data.txt");
	copy(istream_iterator<int>(fin), istream_iterator<int>(), inserter(array, array.begin()));
	fin.close();
	ofstream fout("output.txt");
	copy(array.begin(), array.end(), ostream_iterator<int>(fout, "\n"));
	fout.close();
	return 0;
}