import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
		sc.close();
		int bInt = Integer.valueOf(b.replace(".", ""));
		System.out.println(a*bInt/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();
		String b = sc.next();
		sc.close();
		int bInt = Integer.valueOf(b.replace(".", ""));
		System.out.println(a*bInt/100);

	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
		sc.close();
		int bInt = Integer.valueOf(b.replace(".", ""));
		System.out.println(a*bInt/100);

	} main {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
		sc.close();
		int bInt = Integer.valueOf(b.replace(".", ""));
		System.out.println(a*bInt/100);

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc String b = sc.next(); b sc.next() sc.next sc sc.close() sc.close sc int bInt = Integer.valueOf(b.replace(".", "")); bInt Integer.valueOf(b.replace(".", "")) Integer.valueOf Integer b.replace(".", "") b.replace b "." "" System.out.println(a*bInt/100) System.out.println System.out System System.out a*bInt/100 a*bInt a bInt 100 String[] args args public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
		sc.close();
		int bInt = Integer.valueOf(b.replace(".", ""));
		System.out.println(a*bInt/100);

	}

} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
		sc.close();
		int bInt = Integer.valueOf(b.replace(".", ""));
		System.out.println(a*bInt/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();
		String b = sc.next();
		sc.close();
		int bInt = Integer.valueOf(b.replace(".", ""));
		System.out.println(a*bInt/100);

	}

}