import 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();
        b*=500;
        int c = (int)b;
        long d = a*c;
		System.out.println(d/500);
	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
        b*=500;
        int c = (int)b;
        long d = a*c;
		System.out.println(d/500);
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
        b*=500;
        int c = (int)b;
        long d = a*c;
		System.out.println(d/500);
	} main {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
        b*=500;
        int c = (int)b;
        long d = a*c;
		System.out.println(d/500);
	} 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 b*=500 b 500 int c = (int)b; c (int)b long d = a*c; d a*c a c System.out.println(d/500) System.out.println System.out System System.out d/500 d 500 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();
        b*=500;
        int c = (int)b;
        long d = a*c;
		System.out.println(d/500);
	}
} public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
        b*=500;
        int c = (int)b;
        long d = a*c;
		System.out.println(d/500);
	}
} Main
import 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();
        b*=500;
        int c = (int)b;
        long d = a*c;
		System.out.println(d/500);
	}
}
