import java.util.*;

public class Main {
 	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		char[] arr = sc.next().toCharArray();
		int speed = 0;
		for (int i = 2; i < arr.length; i++) {
		    speed *= 10;
		    speed += arr[i] - '0';
		}
		int t = sc.nextInt();
		System.out.println(speed * t / 10000);
	}
}