import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    long a = in.nextLong();
    double b = in.nextDouble();
    long flooredB = (long) (b * 100 + 0.5);
    System.out.println(a * flooredB / 100);
    in.close();
  }
} import java.util.Scanner; Scanner java.util public class Main {
  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    long a = in.nextLong();
    double b = in.nextDouble();
    long flooredB = (long) (b * 100 + 0.5);
    System.out.println(a * flooredB / 100);
    in.close();
  }
} Main public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    long a = in.nextLong();
    double b = in.nextDouble();
    long flooredB = (long) (b * 100 + 0.5);
    System.out.println(a * flooredB / 100);
    in.close();
  } main {
    Scanner in = new Scanner(System.in);
    long a = in.nextLong();
    double b = in.nextDouble();
    long flooredB = (long) (b * 100 + 0.5);
    System.out.println(a * flooredB / 100);
    in.close();
  } Scanner in = new Scanner(System.in); in new Scanner(System.in) long a = in.nextLong(); a in.nextLong() in.nextLong in double b = in.nextDouble(); b in.nextDouble() in.nextDouble in long flooredB = (long) (b * 100 + 0.5); flooredB (long) (b * 100 + 0.5) b * 100 b 100 0.5 System.out.println(a * flooredB / 100) System.out.println System.out System System.out a * flooredB / 100 a * flooredB a flooredB 100 in.close() in.close in String[] args args public class Main {
  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    long a = in.nextLong();
    double b = in.nextDouble();
    long flooredB = (long) (b * 100 + 0.5);
    System.out.println(a * flooredB / 100);
    in.close();
  }
} public class Main {
  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    long a = in.nextLong();
    double b = in.nextDouble();
    long flooredB = (long) (b * 100 + 0.5);
    System.out.println(a * flooredB / 100);
    in.close();
  }
} Main
import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    long a = in.nextLong();
    double b = in.nextDouble();
    long flooredB = (long) (b * 100 + 0.5);
    System.out.println(a * flooredB / 100);
    in.close();
  }
}