#include <iostream>
#include <string>
#include <sstream>

using namespace std;

int main() {
	string v;
	int t;
	cin >> v >> t;
	string v4;
	for (size_t i = 0; i < v.size(); ++i) {
		if (v[i] != '.') {
			v4.push_back(v[i]);
		}
	}
	istringstream is(v4);
	int vi;
	is >> vi;
	cout << (vi * t / 10000) << endl;
	return 0;
}