import java.util.Scanner;

public class No350 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String v = sc.next();
		int t = sc.nextInt();
		v = v.substring(2,v.length());
		int V = Integer.parseInt(v);
		System.out.println(V * t /10000);
	}
}