import java.util.Scanner;

public class Main {
	static double eps=1.0E-14;
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scn=new Scanner(System.in);
		long a =scn.nextLong();
		long b =(long)((eps+scn.nextDouble())*100);
		long c =a*b/100;
		System.out.println(c);

	}

} import java.util.Scanner; Scanner java.util public class Main {
	static double eps=1.0E-14;
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scn=new Scanner(System.in);
		long a =scn.nextLong();
		long b =(long)((eps+scn.nextDouble())*100);
		long c =a*b/100;
		System.out.println(c);

	}

} Main static double eps=1.0E-14; eps 1.0E-14 public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scn=new Scanner(System.in);
		long a =scn.nextLong();
		long b =(long)((eps+scn.nextDouble())*100);
		long c =a*b/100;
		System.out.println(c);

	} main {
		// TODO Auto-generated method stub
		Scanner scn=new Scanner(System.in);
		long a =scn.nextLong();
		long b =(long)((eps+scn.nextDouble())*100);
		long c =a*b/100;
		System.out.println(c);

	} Scanner scn=new Scanner(System.in); scn new Scanner(System.in) long a =scn.nextLong(); a scn.nextLong() scn.nextLong scn long b =(long)((eps+scn.nextDouble())*100); b (long)((eps+scn.nextDouble())*100) (eps+scn.nextDouble()) eps scn.nextDouble() scn.nextDouble scn 100 long c =a*b/100; c a*b/100 a*b a b 100 System.out.println(c) System.out.println System.out System System.out c String[] args args public class Main {
	static double eps=1.0E-14;
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scn=new Scanner(System.in);
		long a =scn.nextLong();
		long b =(long)((eps+scn.nextDouble())*100);
		long c =a*b/100;
		System.out.println(c);

	}

} public class Main {
	static double eps=1.0E-14;
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scn=new Scanner(System.in);
		long a =scn.nextLong();
		long b =(long)((eps+scn.nextDouble())*100);
		long c =a*b/100;
		System.out.println(c);

	}

} Main
import java.util.Scanner;

public class Main {
	static double eps=1.0E-14;
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scn=new Scanner(System.in);
		long a =scn.nextLong();
		long b =(long)((eps+scn.nextDouble())*100);
		long c =a*b/100;
		System.out.println(c);

	}

}