import java.math.BigDecimal;
import java.util.*;

public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		BigDecimal a = new BigDecimal(scan.next());
		BigDecimal b = new BigDecimal(scan.next());
		BigDecimal tmp = a.multiply(b);
		long ans = tmp.longValue();
		System.out.print(ans);


	}
}
/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