import java.math.BigDecimal;
import java.util.Scanner;
public class Main {
	public static void main(String[] args)throws Exception{
		Scanner stdIn=new Scanner(System.in);
		String A=stdIn.next();
		String B=stdIn.next();
		BigDecimal a = new BigDecimal(A);
		BigDecimal b = new BigDecimal(B);
		System.out.println(a.multiply(b).setScale(0,java.math.RoundingMode.DOWN));
	}
}

/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