import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc =new Scanner(System.in);
    long A =sc.nextLong();
    String B =sc.next();
    String b[] =B.split("",0);long D;
    D =Integer.parseInt(b[0]+b[2]+b[3]);
    long E =A*D;
    long F =E/100;
    System.out.println(F);
  }
} import java.util.*; util.* java public class Main{
  public static void main(String[] args){
    Scanner sc =new Scanner(System.in);
    long A =sc.nextLong();
    String B =sc.next();
    String b[] =B.split("",0);long D;
    D =Integer.parseInt(b[0]+b[2]+b[3]);
    long E =A*D;
    long F =E/100;
    System.out.println(F);
  }
} Main public static void main(String[] args){
    Scanner sc =new Scanner(System.in);
    long A =sc.nextLong();
    String B =sc.next();
    String b[] =B.split("",0);long D;
    D =Integer.parseInt(b[0]+b[2]+b[3]);
    long E =A*D;
    long F =E/100;
    System.out.println(F);
  } main {
    Scanner sc =new Scanner(System.in);
    long A =sc.nextLong();
    String B =sc.next();
    String b[] =B.split("",0);long D;
    D =Integer.parseInt(b[0]+b[2]+b[3]);
    long E =A*D;
    long F =E/100;
    System.out.println(F);
  } Scanner sc =new Scanner(System.in); sc new Scanner(System.in) long A =sc.nextLong(); A sc.nextLong() sc.nextLong sc String B =sc.next(); B sc.next() sc.next sc String b[] =B.split("",0); b B.split("",0) B.split B "" 0 long D; D D =Integer.parseInt(b[0]+b[2]+b[3]) D Integer.parseInt(b[0]+b[2]+b[3]) Integer.parseInt Integer b[0]+b[2]+b[3] b[0]+b[2]+b[3] b[0] b 0 b[2] b 2 b[3] b 3 long E =A*D; E A*D A D long F =E/100; F E/100 E 100 System.out.println(F) System.out.println System.out System System.out F String[] args args public class Main{
  public static void main(String[] args){
    Scanner sc =new Scanner(System.in);
    long A =sc.nextLong();
    String B =sc.next();
    String b[] =B.split("",0);long D;
    D =Integer.parseInt(b[0]+b[2]+b[3]);
    long E =A*D;
    long F =E/100;
    System.out.println(F);
  }
} public class Main{
  public static void main(String[] args){
    Scanner sc =new Scanner(System.in);
    long A =sc.nextLong();
    String B =sc.next();
    String b[] =B.split("",0);long D;
    D =Integer.parseInt(b[0]+b[2]+b[3]);
    long E =A*D;
    long F =E/100;
    System.out.println(F);
  }
} Main
import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc =new Scanner(System.in);
    long A =sc.nextLong();
    String B =sc.next();
    String b[] =B.split("",0);long D;
    D =Integer.parseInt(b[0]+b[2]+b[3]);
    long E =A*D;
    long F =E/100;
    System.out.println(F);
  }
}