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

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        long a;
        double b;

        a = scanner.nextLong();
        b = scanner.nextDouble();

        BigDecimal bigA = BigDecimal.valueOf(a);
        BigDecimal bigB = BigDecimal.valueOf(b);

        BigDecimal bigResult = bigA.multiply(bigB);

        BigDecimal roundBigResult = bigResult.setScale(0, BigDecimal.ROUND_DOWN);

        System.out.print(roundBigResult);
    }
}

/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