import java.util.*;
import java.util.function.*;
import java.lang.*;
import java.io.*;


public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long Bx100 = Long.valueOf(sc.next().replace(".", ""));

        System.out.println(A*Bx100/100);
    }
} import java.util.*; util.* java import java.util.function.*; function.* java.util import java.lang.*; lang.* java import java.io.*; io.* java public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long Bx100 = Long.valueOf(sc.next().replace(".", ""));

        System.out.println(A*Bx100/100);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long Bx100 = Long.valueOf(sc.next().replace(".", ""));

        System.out.println(A*Bx100/100);
    } main {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long Bx100 = Long.valueOf(sc.next().replace(".", ""));

        System.out.println(A*Bx100/100);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long A = sc.nextLong(); A sc.nextLong() sc.nextLong sc long Bx100 = Long.valueOf(sc.next().replace(".", "")); Bx100 Long.valueOf(sc.next().replace(".", "")) Long.valueOf Long sc.next().replace(".", "") sc.next().replace sc.next() sc.next sc "." "" System.out.println(A*Bx100/100) System.out.println System.out System System.out A*Bx100/100 A*Bx100 A Bx100 100 String[] args args public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long Bx100 = Long.valueOf(sc.next().replace(".", ""));

        System.out.println(A*Bx100/100);
    }
} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long Bx100 = Long.valueOf(sc.next().replace(".", ""));

        System.out.println(A*Bx100/100);
    }
} Main
import java.util.*;
import java.util.function.*;
import java.lang.*;
import java.io.*;


public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long Bx100 = Long.valueOf(sc.next().replace(".", ""));

        System.out.println(A*Bx100/100);
    }
}
