#include <iostream>
#include <vector>
#include <unordered_map>

int main(int argc, char** argv) {

	std::vector<int> foo = {0, 0, 1, 1, 1, 2, 2};
	std::unordered_map<int, int> counts;


	for (auto& v : foo) {
		if (counts.find(v) == counts.end()) {
			counts[v] = 0;
		}
		counts[v]++;
	}

	for (auto& v : counts) {
		if (v.second % 2 != 0) {
			std::cout << v.first << std::endl;
		}
	}

	return 0;
}