import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
        String s = b.substring(0,1)+b.substring(2,4);
        int c = Integer.parseInt(s);
        long d = a*c;
		System.out.println(d/100);
	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
        String s = b.substring(0,1)+b.substring(2,4);
        int c = Integer.parseInt(s);
        long d = a*c;
		System.out.println(d/100);
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
        String s = b.substring(0,1)+b.substring(2,4);
        int c = Integer.parseInt(s);
        long d = a*c;
		System.out.println(d/100);
	} main {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
        String s = b.substring(0,1)+b.substring(2,4);
        int c = Integer.parseInt(s);
        long d = a*c;
		System.out.println(d/100);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc String b = sc.next(); b sc.next() sc.next sc String s = b.substring(0,1)+b.substring(2,4); s b.substring(0,1)+b.substring(2,4) b.substring(0,1) b.substring b 0 1 b.substring(2,4) b.substring b 2 4 int c = Integer.parseInt(s); c Integer.parseInt(s) Integer.parseInt Integer s long d = a*c; d a*c a c System.out.println(d/100) System.out.println System.out System System.out d/100 d 100 String[] args args public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
        String s = b.substring(0,1)+b.substring(2,4);
        int c = Integer.parseInt(s);
        long d = a*c;
		System.out.println(d/100);
	}
} public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
        String s = b.substring(0,1)+b.substring(2,4);
        int c = Integer.parseInt(s);
        long d = a*c;
		System.out.println(d/100);
	}
} Main
import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
        String s = b.substring(0,1)+b.substring(2,4);
        int c = Integer.parseInt(s);
        long d = a*c;
		System.out.println(d/100);
	}
}