import java.util.*;
import java.io.*;

public class Main {
    public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
	long a = sc.nextLong();
	double b = sc.nextDouble();
	sc.close();
	long c = (long)Math.round(b * 100);
	long d = a * c;
	System.out.println(d / 100);
    }
} import java.util.*; util.* java import java.io.*; io.* java public class Main {
    public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
	long a = sc.nextLong();
	double b = sc.nextDouble();
	sc.close();
	long c = (long)Math.round(b * 100);
	long d = a * c;
	System.out.println(d / 100);
    }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
	long a = sc.nextLong();
	double b = sc.nextDouble();
	sc.close();
	long c = (long)Math.round(b * 100);
	long d = a * c;
	System.out.println(d / 100);
    } main {
    Scanner sc = new Scanner(System.in);
	long a = sc.nextLong();
	double b = sc.nextDouble();
	sc.close();
	long c = (long)Math.round(b * 100);
	long d = a * c;
	System.out.println(d / 100);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc double b = sc.nextDouble(); b sc.nextDouble() sc.nextDouble sc sc.close() sc.close sc long c = (long)Math.round(b * 100); c (long)Math.round(b * 100) Math.round Math b * 100 b 100 long d = a * c; d a * c a c System.out.println(d / 100) System.out.println System.out System System.out d / 100 d 100 String[] args args public class Main {
    public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
	long a = sc.nextLong();
	double b = sc.nextDouble();
	sc.close();
	long c = (long)Math.round(b * 100);
	long d = a * c;
	System.out.println(d / 100);
    }
} public class Main {
    public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
	long a = sc.nextLong();
	double b = sc.nextDouble();
	sc.close();
	long c = (long)Math.round(b * 100);
	long d = a * c;
	System.out.println(d / 100);
    }
} Main
import java.util.*;
import java.io.*;

public class Main {
    public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
	long a = sc.nextLong();
	double b = sc.nextDouble();
	sc.close();
	long c = (long)Math.round(b * 100);
	long d = a * c;
	System.out.println(d / 100);
    }
}