import java.util.Arrays;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.Set;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		final int v = Integer.parseInt(sc.next().replace(".", ""));
		final int t = sc.nextInt();
		
		System.out.println((v * t) / 10000);
	}

}