#include<vector>
#include<iostream>

using namespace std;

// for more information look up http://ejudge.lksh.ru/lang_docs/en.cppreference.com/w/cpp/container/vector.html

int main() {
	vector<int> a;
	a.push_back(5);
	a.push_back(2);
	a.push_back(1);
	cout << "size = " << a.size() << endl;
	cout << "is vector empty? " << a.empty() << endl;
	cout << a.back() << endl;
	a.pop_back();
	cout << a.back() << endl;
	a.pop_back();
	cout << a.back() << endl;
	a.pop_back();
	cout << "is vector empty? " << a.empty() << endl;

	vector<string> b;
	b.push_back("hello\n");
	cout << b.back();

	return 0;
}