import java.util.*;
import java.io.*;

public class Main {
    public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
	long a = sc.nextLong();
	double b = sc.nextDouble();
	sc.close();
	long c = (long)Math.round(b * 100);
	long d = a * c;
	System.out.println(d / 100);
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz