import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);

		long a = scan.nextLong();
		long b = (long)(scan.nextDouble() * 100 + 0.001);


		System.out.println((a * b)/100);
	}
} 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();
		long b = (long)(scan.nextDouble() * 100 + 0.001);


		System.out.println((a * b)/100);
	}
} Main public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);

		long a = scan.nextLong();
		long b = (long)(scan.nextDouble() * 100 + 0.001);


		System.out.println((a * b)/100);
	} main {
		Scanner scan = new Scanner(System.in);

		long a = scan.nextLong();
		long b = (long)(scan.nextDouble() * 100 + 0.001);


		System.out.println((a * b)/100);
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) long a = scan.nextLong(); a scan.nextLong() scan.nextLong scan long b = (long)(scan.nextDouble() * 100 + 0.001); b (long)(scan.nextDouble() * 100 + 0.001) scan.nextDouble() * 100 scan.nextDouble() scan.nextDouble scan 100 0.001 System.out.println((a * b)/100) System.out.println System.out System System.out (a * b)/100 (a * b) a b 100 String[] args args public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);

		long a = scan.nextLong();
		long b = (long)(scan.nextDouble() * 100 + 0.001);


		System.out.println((a * b)/100);
	}
} public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);

		long a = scan.nextLong();
		long b = (long)(scan.nextDouble() * 100 + 0.001);


		System.out.println((a * b)/100);
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);

		long a = scan.nextLong();
		long b = (long)(scan.nextDouble() * 100 + 0.001);


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