import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		String str[] = br.readLine().split(" ");

		long a = Long.parseLong(str[0]);
		double b = Double.parseDouble(str[1]);

		long c = (long) b * 100;
		long d = a * (long) (b * 100 + 0.001) / 100;
		System.out.println(d);
	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		String str[] = br.readLine().split(" ");

		long a = Long.parseLong(str[0]);
		double b = Double.parseDouble(str[1]);

		long c = (long) b * 100;
		long d = a * (long) (b * 100 + 0.001) / 100;
		System.out.println(d);
	}
} Main public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		String str[] = br.readLine().split(" ");

		long a = Long.parseLong(str[0]);
		double b = Double.parseDouble(str[1]);

		long c = (long) b * 100;
		long d = a * (long) (b * 100 + 0.001) / 100;
		System.out.println(d);
	} main {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		String str[] = br.readLine().split(" ");

		long a = Long.parseLong(str[0]);
		double b = Double.parseDouble(str[1]);

		long c = (long) b * 100;
		long d = a * (long) (b * 100 + 0.001) / 100;
		System.out.println(d);
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) String str[] = br.readLine().split(" "); str br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " long a = Long.parseLong(str[0]); a Long.parseLong(str[0]) Long.parseLong Long str[0] str 0 double b = Double.parseDouble(str[1]); b Double.parseDouble(str[1]) Double.parseDouble Double str[1] str 1 long c = (long) b * 100; c (long) b * 100 (long) b 100 long d = a * (long) (b * 100 + 0.001) / 100; d a * (long) (b * 100 + 0.001) / 100 a * (long) (b * 100 + 0.001) a (long) (b * 100 + 0.001) b * 100 b 100 0.001 100 System.out.println(d) System.out.println System.out System System.out d String[] args args public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		String str[] = br.readLine().split(" ");

		long a = Long.parseLong(str[0]);
		double b = Double.parseDouble(str[1]);

		long c = (long) b * 100;
		long d = a * (long) (b * 100 + 0.001) / 100;
		System.out.println(d);
	}
} public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		String str[] = br.readLine().split(" ");

		long a = Long.parseLong(str[0]);
		double b = Double.parseDouble(str[1]);

		long c = (long) b * 100;
		long d = a * (long) (b * 100 + 0.001) / 100;
		System.out.println(d);
	}
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		String str[] = br.readLine().split(" ");

		long a = Long.parseLong(str[0]);
		double b = Double.parseDouble(str[1]);

		long c = (long) b * 100;
		long d = a * (long) (b * 100 + 0.001) / 100;
		System.out.println(d);
	}
}