import java.util.Scanner;

/*

*/

public class Main {
    public static void main(String[] args){

        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        double b = sc.nextDouble();
        long bb = Math.round(b * 100);
//        System.out.println(b * 100);
//        System.out.println(Math.floor(b * 100));
        long ans = a * bb / 100;

        System.out.println(ans);

    }
} import java.util.Scanner; Scanner 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 bb = Math.round(b * 100);
//        System.out.println(b * 100);
//        System.out.println(Math.floor(b * 100));
        long ans = a * bb / 100;

        System.out.println(ans);

    }
} Main public static void main(String[] args){

        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        double b = sc.nextDouble();
        long bb = Math.round(b * 100);
//        System.out.println(b * 100);
//        System.out.println(Math.floor(b * 100));
        long ans = a * bb / 100;

        System.out.println(ans);

    } main {

        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        double b = sc.nextDouble();
        long bb = Math.round(b * 100);
//        System.out.println(b * 100);
//        System.out.println(Math.floor(b * 100));
        long ans = a * bb / 100;

        System.out.println(ans);

    } 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 bb = Math.round(b * 100); bb Math.round(b * 100) Math.round Math b * 100 b 100 long ans = a * bb / 100; ans a * bb / 100 a * bb a bb 100 System.out.println(ans) System.out.println System.out System System.out ans 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 bb = Math.round(b * 100);
//        System.out.println(b * 100);
//        System.out.println(Math.floor(b * 100));
        long ans = a * bb / 100;

        System.out.println(ans);

    }
} public class Main {
    public static void main(String[] args){

        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        double b = sc.nextDouble();
        long bb = Math.round(b * 100);
//        System.out.println(b * 100);
//        System.out.println(Math.floor(b * 100));
        long ans = a * bb / 100;

        System.out.println(ans);

    }
} Main
import java.util.Scanner;

/*

*/

public class Main {
    public static void main(String[] args){

        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        double b = sc.nextDouble();
        long bb = Math.round(b * 100);
//        System.out.println(b * 100);
//        System.out.println(Math.floor(b * 100));
        long ans = a * bb / 100;

        System.out.println(ans);

    }
}