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 scan =new Scanner(System.in);
		BigDecimal A = scan.nextBigDecimal();
		BigDecimal B= scan.nextBigDecimal();
		BigDecimal seki = B.multiply(A);
		long C = seki.longValue();
		System.out.println(C);
	}
}
/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