import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String[] bstr = sc.next().split("\\.");
        long b1 = Long.valueOf(bstr[0]) * 100;
        long b2 = Long.valueOf(bstr[1]);
        System.out.println(a * (b1 + b2) / 100);
    }

} 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();
        String[] bstr = sc.next().split("\\.");
        long b1 = Long.valueOf(bstr[0]) * 100;
        long b2 = Long.valueOf(bstr[1]);
        System.out.println(a * (b1 + b2) / 100);
    }

} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String[] bstr = sc.next().split("\\.");
        long b1 = Long.valueOf(bstr[0]) * 100;
        long b2 = Long.valueOf(bstr[1]);
        System.out.println(a * (b1 + b2) / 100);
    } main {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String[] bstr = sc.next().split("\\.");
        long b1 = Long.valueOf(bstr[0]) * 100;
        long b2 = Long.valueOf(bstr[1]);
        System.out.println(a * (b1 + b2) / 100);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc String[] bstr = sc.next().split("\\."); bstr sc.next().split("\\.") sc.next().split sc.next() sc.next sc "\\." long b1 = Long.valueOf(bstr[0]) * 100; b1 Long.valueOf(bstr[0]) * 100 Long.valueOf(bstr[0]) Long.valueOf Long bstr[0] bstr 0 100 long b2 = Long.valueOf(bstr[1]); b2 Long.valueOf(bstr[1]) Long.valueOf Long bstr[1] bstr 1 System.out.println(a * (b1 + b2) / 100) System.out.println System.out System System.out a * (b1 + b2) / 100 a * (b1 + b2) a (b1 + b2) b1 b2 100 String[] args args public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String[] bstr = sc.next().split("\\.");
        long b1 = Long.valueOf(bstr[0]) * 100;
        long b2 = Long.valueOf(bstr[1]);
        System.out.println(a * (b1 + b2) / 100);
    }

} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String[] bstr = sc.next().split("\\.");
        long b1 = Long.valueOf(bstr[0]) * 100;
        long b2 = Long.valueOf(bstr[1]);
        System.out.println(a * (b1 + b2) / 100);
    }

} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String[] bstr = sc.next().split("\\.");
        long b1 = Long.valueOf(bstr[0]) * 100;
        long b2 = Long.valueOf(bstr[1]);
        System.out.println(a * (b1 + b2) / 100);
    }

}
