import java.util.Scanner;


public class Main_yukicoder350 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        String s = sc.next();
        int t = sc.nextInt();

        int v = Integer.parseInt(s.substring(2, 6));

        System.out.println(v * t / 10000);

        sc.close();
    }
}