import java.util.*;
import java.util.regex.Pattern;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        long b = Long.parseLong(sc.next().replace(".", ""));
        System.out.println(a * b / 100);
    }
} import java.util.*; util.* java import java.util.regex.Pattern; Pattern java.util.regex public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        long b = Long.parseLong(sc.next().replace(".", ""));
        System.out.println(a * b / 100);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        long b = Long.parseLong(sc.next().replace(".", ""));
        System.out.println(a * b / 100);
    } main {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        long b = Long.parseLong(sc.next().replace(".", ""));
        System.out.println(a * b / 100);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc long b = Long.parseLong(sc.next().replace(".", "")); b Long.parseLong(sc.next().replace(".", "")) Long.parseLong Long sc.next().replace(".", "") sc.next().replace sc.next() sc.next sc "." "" System.out.println(a * b / 100) System.out.println System.out System System.out a * b / 100 a * b a b 100 String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        long b = Long.parseLong(sc.next().replace(".", ""));
        System.out.println(a * b / 100);
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        long b = Long.parseLong(sc.next().replace(".", ""));
        System.out.println(a * b / 100);
    }
} Main
import java.util.*;
import java.util.regex.Pattern;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        long b = Long.parseLong(sc.next().replace(".", ""));
        System.out.println(a * b / 100);
    }
}