#include <algorithm>
#include <complex>
#include <functional>
#include <iostream>
#include <map>
#include <memory>
#include <queue>
#include <regex>
#include <sstream>
#include <string>
#include <thread>
#include <tuple>
#include <type_traits>
#include <vector>

#define rep(i, n) for (int i = 0; i < (n); i++)
using namespace std;
using ll = long long;

int main() {
    ios::sync_with_stdio(false);
  
  	long double a,b;
	cin>>a>>b;
	long long temp=floor(a*b);
	cout<<temp;

    return 0;
}
