import java.util.Scanner;

public class Main {

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

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

public class Main {

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