import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		int x = (int) (b * 100 + 0.5);

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

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

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		int x = (int) (b * 100 + 0.5);

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

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		int x = (int) (b * 100 + 0.5);

		System.out.println((long) (a * x) / 100);
	} main {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		int x = (int) (b * 100 + 0.5);

		System.out.println((long) (a * x) / 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 int x = (int) (b * 100 + 0.5); x (int) (b * 100 + 0.5) b * 100 b 100 0.5 System.out.println((long) (a * x) / 100) System.out.println System.out System System.out (long) (a * x) / 100 (long) (a * x) a x 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();
		int x = (int) (b * 100 + 0.5);

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

} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		int x = (int) (b * 100 + 0.5);

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

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		int x = (int) (b * 100 + 0.5);

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

}
