import java.util.Scanner;


class Main{
 public static void main(String args[]){
   Scanner sc = new Scanner(System.in);
   long A = sc.nextLong();
   double B = sc.nextDouble();
   long b = (long) (B*(double)100+0.5);

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

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

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

   System.out.println(A*b/(long)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 b = (long) (B*(double)100+0.5); b (long) (B*(double)100+0.5) B*(double)100 B (double)100 0.5 System.out.println(A*b/(long)100) System.out.println System.out System System.out A*b/(long)100 A*b A b (long)100 String args[] args
import java.util.Scanner;


class Main{
 public static void main(String args[]){
   Scanner sc = new Scanner(System.in);
   long A = sc.nextLong();
   double B = sc.nextDouble();
   long b = (long) (B*(double)100+0.5);

   System.out.println(A*b/(long)100);
 
 }
}

