import java.util.Scanner;

public class Main {

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

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