#include <iostream>

using namespace std;

int main() {

	double ownDog, neighborDog, leva;
	cin >> ownDog >> neighborDog;

	leva = (ownDog * 2.50) + (4 * neighborDog);

	cout.setf(ios::fixed);
	cout.precision(2);

	cout << leva << " lv.";



	return 0;
}