import java.util.Scanner;
import java.math.*;
public class Main{
        public static void main(String[] args){
                final Scanner cin=new Scanner(System.in);
                long a=cin.nextLong();
                double b=cin.nextDouble();
                long k=(long)Math.round(b*100);
                long mul=(a*k);
                System.out.print(mul/100);
        }   
} import java.util.Scanner; Scanner java.util import java.math.*; math.* java public class Main{
        public static void main(String[] args){
                final Scanner cin=new Scanner(System.in);
                long a=cin.nextLong();
                double b=cin.nextDouble();
                long k=(long)Math.round(b*100);
                long mul=(a*k);
                System.out.print(mul/100);
        }   
} Main public static void main(String[] args){
                final Scanner cin=new Scanner(System.in);
                long a=cin.nextLong();
                double b=cin.nextDouble();
                long k=(long)Math.round(b*100);
                long mul=(a*k);
                System.out.print(mul/100);
        } main {
                final Scanner cin=new Scanner(System.in);
                long a=cin.nextLong();
                double b=cin.nextDouble();
                long k=(long)Math.round(b*100);
                long mul=(a*k);
                System.out.print(mul/100);
        } final Scanner cin=new Scanner(System.in); cin new Scanner(System.in) long a=cin.nextLong(); a cin.nextLong() cin.nextLong cin double b=cin.nextDouble(); b cin.nextDouble() cin.nextDouble cin long k=(long)Math.round(b*100); k (long)Math.round(b*100) Math.round Math b*100 b 100 long mul=(a*k); mul (a*k) a k System.out.print(mul/100) System.out.print System.out System System.out mul/100 mul 100 String[] args args public class Main{
        public static void main(String[] args){
                final Scanner cin=new Scanner(System.in);
                long a=cin.nextLong();
                double b=cin.nextDouble();
                long k=(long)Math.round(b*100);
                long mul=(a*k);
                System.out.print(mul/100);
        }   
} public class Main{
        public static void main(String[] args){
                final Scanner cin=new Scanner(System.in);
                long a=cin.nextLong();
                double b=cin.nextDouble();
                long k=(long)Math.round(b*100);
                long mul=(a*k);
                System.out.print(mul/100);
        }   
} Main
import java.util.Scanner;
import java.math.*;
public class Main{
        public static void main(String[] args){
                final Scanner cin=new Scanner(System.in);
                long a=cin.nextLong();
                double b=cin.nextDouble();
                long k=(long)Math.round(b*100);
                long mul=(a*k);
                System.out.print(mul/100);
        }   
}
