import java.math.BigDecimal;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        try (Scanner scan = new Scanner(System.in)) {
            BigDecimal d = new BigDecimal(scan.next());
            BigDecimal t = new BigDecimal(scan.next());
            
            System.out.format("%.0f",Math.floor(d.multiply(t).floatValue()));
        }
    }
}