
import java.util.*;

public class Main {

	public static void main(String[] args) {
		Main main = new Main();
		main.run();
	}

	public void run() {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		long lb = Math.round(b*100);
		long ans = a*lb/100;
		System.out.println(ans);
		sc.close();
	}


} import java.util.*; util.* java public class Main {

	public static void main(String[] args) {
		Main main = new Main();
		main.run();
	}

	public void run() {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		long lb = Math.round(b*100);
		long ans = a*lb/100;
		System.out.println(ans);
		sc.close();
	}


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

	public static void main(String[] args) {
		Main main = new Main();
		main.run();
	}

	public void run() {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		long lb = Math.round(b*100);
		long ans = a*lb/100;
		System.out.println(ans);
		sc.close();
	}


} public class Main {

	public static void main(String[] args) {
		Main main = new Main();
		main.run();
	}

	public void run() {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		long lb = Math.round(b*100);
		long ans = a*lb/100;
		System.out.println(ans);
		sc.close();
	}


} Main

import java.util.*;

public class Main {

	public static void main(String[] args) {
		Main main = new Main();
		main.run();
	}

	public void run() {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		long lb = Math.round(b*100);
		long ans = a*lb/100;
		System.out.println(ans);
		sc.close();
	}


}