import java.util.Scanner;

public class Main {
    public static void main(String args[]) {
        Scanner scn = new Scanner(System.in);
        long a = scn.nextLong();
        double b = scn.nextDouble();
        double b2 = Math.round(b*100);

        long B = (long)b2;

        long ans = a*B;

        long ans2 = ans/100;

        System.out.println(ans2);

        scn.close();


    }


} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String args[]) {
        Scanner scn = new Scanner(System.in);
        long a = scn.nextLong();
        double b = scn.nextDouble();
        double b2 = Math.round(b*100);

        long B = (long)b2;

        long ans = a*B;

        long ans2 = ans/100;

        System.out.println(ans2);

        scn.close();


    }


} Main public static void main(String args[]) {
        Scanner scn = new Scanner(System.in);
        long a = scn.nextLong();
        double b = scn.nextDouble();
        double b2 = Math.round(b*100);

        long B = (long)b2;

        long ans = a*B;

        long ans2 = ans/100;

        System.out.println(ans2);

        scn.close();


    } main {
        Scanner scn = new Scanner(System.in);
        long a = scn.nextLong();
        double b = scn.nextDouble();
        double b2 = Math.round(b*100);

        long B = (long)b2;

        long ans = a*B;

        long ans2 = ans/100;

        System.out.println(ans2);

        scn.close();


    } Scanner scn = new Scanner(System.in); scn new Scanner(System.in) long a = scn.nextLong(); a scn.nextLong() scn.nextLong scn double b = scn.nextDouble(); b scn.nextDouble() scn.nextDouble scn double b2 = Math.round(b*100); b2 Math.round(b*100) Math.round Math b*100 b 100 long B = (long)b2; B (long)b2 long ans = a*B; ans a*B a B long ans2 = ans/100; ans2 ans/100 ans 100 System.out.println(ans2) System.out.println System.out System System.out ans2 scn.close() scn.close scn String args[] args public class Main {
    public static void main(String args[]) {
        Scanner scn = new Scanner(System.in);
        long a = scn.nextLong();
        double b = scn.nextDouble();
        double b2 = Math.round(b*100);

        long B = (long)b2;

        long ans = a*B;

        long ans2 = ans/100;

        System.out.println(ans2);

        scn.close();


    }


} public class Main {
    public static void main(String args[]) {
        Scanner scn = new Scanner(System.in);
        long a = scn.nextLong();
        double b = scn.nextDouble();
        double b2 = Math.round(b*100);

        long B = (long)b2;

        long ans = a*B;

        long ans2 = ans/100;

        System.out.println(ans2);

        scn.close();


    }


} Main
import java.util.Scanner;

public class Main {
    public static void main(String args[]) {
        Scanner scn = new Scanner(System.in);
        long a = scn.nextLong();
        double b = scn.nextDouble();
        double b2 = Math.round(b*100);

        long B = (long)b2;

        long ans = a*B;

        long ans2 = ans/100;

        System.out.println(ans2);

        scn.close();


    }


}