import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        Long A = Long.parseLong(sc.next());
        String B = sc.next();
        String[] B_array = B.split("\\.",-1);
        System.out.println(A*Long.parseLong(B_array[0]) +(A*Integer.parseInt(B_array[1]))/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 = Long.parseLong(sc.next());
        String B = sc.next();
        String[] B_array = B.split("\\.",-1);
        System.out.println(A*Long.parseLong(B_array[0]) +(A*Integer.parseInt(B_array[1]))/100 );
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        Long A = Long.parseLong(sc.next());
        String B = sc.next();
        String[] B_array = B.split("\\.",-1);
        System.out.println(A*Long.parseLong(B_array[0]) +(A*Integer.parseInt(B_array[1]))/100 );
    } main {
        Scanner sc = new Scanner(System.in);
        Long A = Long.parseLong(sc.next());
        String B = sc.next();
        String[] B_array = B.split("\\.",-1);
        System.out.println(A*Long.parseLong(B_array[0]) +(A*Integer.parseInt(B_array[1]))/100 );
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) Long A = Long.parseLong(sc.next()); A Long.parseLong(sc.next()) Long.parseLong Long sc.next() sc.next sc String B = sc.next(); B sc.next() sc.next sc String[] B_array = B.split("\\.",-1); B_array B.split("\\.",-1) B.split B "\\." -1 1 System.out.println(A*Long.parseLong(B_array[0]) +(A*Integer.parseInt(B_array[1]))/100 ) System.out.println System.out System System.out A*Long.parseLong(B_array[0]) +(A*Integer.parseInt(B_array[1]))/100 A*Long.parseLong(B_array[0]) A Long.parseLong(B_array[0]) Long.parseLong Long B_array[0] B_array 0 (A*Integer.parseInt(B_array[1]))/100 (A*Integer.parseInt(B_array[1])) A Integer.parseInt(B_array[1]) Integer.parseInt Integer B_array[1] B_array 1 100 String[] args args public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        Long A = Long.parseLong(sc.next());
        String B = sc.next();
        String[] B_array = B.split("\\.",-1);
        System.out.println(A*Long.parseLong(B_array[0]) +(A*Integer.parseInt(B_array[1]))/100 );
    }
} public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        Long A = Long.parseLong(sc.next());
        String B = sc.next();
        String[] B_array = B.split("\\.",-1);
        System.out.println(A*Long.parseLong(B_array[0]) +(A*Integer.parseInt(B_array[1]))/100 );
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        Long A = Long.parseLong(sc.next());
        String B = sc.next();
        String[] B_array = B.split("\\.",-1);
        System.out.println(A*Long.parseLong(B_array[0]) +(A*Integer.parseInt(B_array[1]))/100 );
    }
}