import java.util.Scanner;

public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		long value1 = scan.nextLong();
		long value2 = (long) (scan.nextDouble() * 100 + 0.001);
		long sum = value1 * value2 / 100;

		scan.close();
		System.out.println(sum);
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		long value1 = scan.nextLong();
		long value2 = (long) (scan.nextDouble() * 100 + 0.001);
		long sum = value1 * value2 / 100;

		scan.close();
		System.out.println(sum);
	}
} Main public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		long value1 = scan.nextLong();
		long value2 = (long) (scan.nextDouble() * 100 + 0.001);
		long sum = value1 * value2 / 100;

		scan.close();
		System.out.println(sum);
	} main {
		Scanner scan = new Scanner(System.in);
		long value1 = scan.nextLong();
		long value2 = (long) (scan.nextDouble() * 100 + 0.001);
		long sum = value1 * value2 / 100;

		scan.close();
		System.out.println(sum);
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) long value1 = scan.nextLong(); value1 scan.nextLong() scan.nextLong scan long value2 = (long) (scan.nextDouble() * 100 + 0.001); value2 (long) (scan.nextDouble() * 100 + 0.001) scan.nextDouble() * 100 scan.nextDouble() scan.nextDouble scan 100 0.001 long sum = value1 * value2 / 100; sum value1 * value2 / 100 value1 * value2 value1 value2 100 scan.close() scan.close scan System.out.println(sum) System.out.println System.out System System.out sum String args[] args public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		long value1 = scan.nextLong();
		long value2 = (long) (scan.nextDouble() * 100 + 0.001);
		long sum = value1 * value2 / 100;

		scan.close();
		System.out.println(sum);
	}
} public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		long value1 = scan.nextLong();
		long value2 = (long) (scan.nextDouble() * 100 + 0.001);
		long sum = value1 * value2 / 100;

		scan.close();
		System.out.println(sum);
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		long value1 = scan.nextLong();
		long value2 = (long) (scan.nextDouble() * 100 + 0.001);
		long sum = value1 * value2 / 100;

		scan.close();
		System.out.println(sum);
	}
}
