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

public class Main {
	//java11

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		String A = sc.next();
		String B = sc.next();

		BigDecimal bA = new BigDecimal(A);
		BigDecimal bB = new BigDecimal(B);
		BigDecimal ans = bA.multiply(bB);
		ans = ans.setScale(0, RoundingMode.DOWN);

		System.out.println(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