
import java.util.*;
 interface aisatu{
	final String str="こんにちは";
	void mesod();
}

public class Main {
	static public void main(String args[]){
		Scanner sc=new Scanner(System.in);
		
		long a=sc.nextLong();
		int b=(int)(sc.nextDouble()*100+0.01);
		
		System.out.print((a*b)/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