import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.Scanner;

public class Main{

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ

		Scanner sc=new Scanner(System.in);
		BigDecimal A=new BigDecimal(sc.nextLong());
		BigDecimal B=new BigDecimal(sc.next());
		
		BigDecimal result=A.multiply(B);
		BigDecimal BigResult=result.setScale(0,RoundingMode.DOWN);
		System.out.println(BigResult);
	
	}

}
/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