#include <iostream>
#include <map>
using namespace std;

int main() {
	std::map<int, int> myMap;
	
	cout << "myMap size = " << myMap.size() << endl;
	
	myMap[0];
	myMap[1];
	myMap[2];
	myMap[3];
	
	cout << "myMap size = " << myMap.size() << endl;
	
	return 0;
}