
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		long a = scan.nextLong();
		double b = scan.nextDouble();
		double b2 = Math.round(b*100);

		long re = (long)b2;


		System.out.println((long)(a*re)/100);

		scan.close();

	}

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

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		long a = scan.nextLong();
		double b = scan.nextDouble();
		double b2 = Math.round(b*100);

		long re = (long)b2;


		System.out.println((long)(a*re)/100);

		scan.close();

	}

} Main public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		long a = scan.nextLong();
		double b = scan.nextDouble();
		double b2 = Math.round(b*100);

		long re = (long)b2;


		System.out.println((long)(a*re)/100);

		scan.close();

	} main {

		Scanner scan = new Scanner(System.in);

		long a = scan.nextLong();
		double b = scan.nextDouble();
		double b2 = Math.round(b*100);

		long re = (long)b2;


		System.out.println((long)(a*re)/100);

		scan.close();

	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) long a = scan.nextLong(); a scan.nextLong() scan.nextLong scan double b = scan.nextDouble(); b scan.nextDouble() scan.nextDouble scan double b2 = Math.round(b*100); b2 Math.round(b*100) Math.round Math b*100 b 100 long re = (long)b2; re (long)b2 System.out.println((long)(a*re)/100) System.out.println System.out System System.out (long)(a*re)/100 (long)(a*re) a re 100 scan.close() scan.close scan String[] args args public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		long a = scan.nextLong();
		double b = scan.nextDouble();
		double b2 = Math.round(b*100);

		long re = (long)b2;


		System.out.println((long)(a*re)/100);

		scan.close();

	}

} public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		long a = scan.nextLong();
		double b = scan.nextDouble();
		double b2 = Math.round(b*100);

		long re = (long)b2;


		System.out.println((long)(a*re)/100);

		scan.close();

	}

} Main

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		long a = scan.nextLong();
		double b = scan.nextDouble();
		double b2 = Math.round(b*100);

		long re = (long)b2;


		System.out.println((long)(a*re)/100);

		scan.close();

	}

}
