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

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

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

  } main {
    Scanner sc = new Scanner(System.in);
    long a = sc.nextLong();
    double b = sc.nextDouble();
    long ans = a * (long)(b*100+0.5);
    System.out.println(ans/100);

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

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

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

  }
}
