
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        final long A = sc.nextLong();
        String B = sc.next();
        int b_x = Integer.valueOf(B.substring(0, 1)), b_y = Integer.parseInt(B.substring(2));
        long a_x = A * b_x;
        long a_y = A * b_y / 100;
        System.out.println(a_x + a_y);
    }
}

/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