import java.util.*;
import java.io.PrintWriter;
import java.math.*;
public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		BigDecimal a=BigDecimal.valueOf(sc.nextLong());
		BigDecimal b=BigDecimal.valueOf(sc.nextDouble());
	
		System.out.println(a.multiply(b).longValue());
	}
}

/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