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

public class Main {

	public static void main(final String[] args) {
		Scanner sc = new Scanner(System.in);
		long A = sc.nextLong();
		String B = sc.next(); // 文字列で受け取る
		sc.close();
		BigDecimal a = new BigDecimal(A);
		BigDecimal b = new BigDecimal(B);
		prtln(a.multiply(b).toBigInteger());
	}

	public static <T> void prtln(T t) { System.out.println(t); }
} import java.math.BigDecimal; BigDecimal java.math import java.util.Scanner; Scanner java.util public class Main {

	public static void main(final String[] args) {
		Scanner sc = new Scanner(System.in);
		long A = sc.nextLong();
		String B = sc.next(); // 文字列で受け取る
		sc.close();
		BigDecimal a = new BigDecimal(A);
		BigDecimal b = new BigDecimal(B);
		prtln(a.multiply(b).toBigInteger());
	}

	public static <T> void prtln(T t) { System.out.println(t); }
} Main public static void main(final String[] args) {
		Scanner sc = new Scanner(System.in);
		long A = sc.nextLong();
		String B = sc.next(); // 文字列で受け取る
		sc.close();
		BigDecimal a = new BigDecimal(A);
		BigDecimal b = new BigDecimal(B);
		prtln(a.multiply(b).toBigInteger());
	} main {
		Scanner sc = new Scanner(System.in);
		long A = sc.nextLong();
		String B = sc.next(); // 文字列で受け取る
		sc.close();
		BigDecimal a = new BigDecimal(A);
		BigDecimal b = new BigDecimal(B);
		prtln(a.multiply(b).toBigInteger());
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long A = sc.nextLong(); A sc.nextLong() sc.nextLong sc String B = sc.next(); B sc.next() sc.next sc sc.close() sc.close sc BigDecimal a = new BigDecimal(A); a new BigDecimal(A) BigDecimal b = new BigDecimal(B); b new BigDecimal(B) prtln(a.multiply(b).toBigInteger()) prtln a.multiply(b).toBigInteger() a.multiply(b).toBigInteger a.multiply(b) a.multiply a b final String[] args args public static <T> void prtln(T t) { System.out.println(t); } prtln { System.out.println(t); } System.out.println(t) System.out.println System.out System System.out t T t t public class Main {

	public static void main(final String[] args) {
		Scanner sc = new Scanner(System.in);
		long A = sc.nextLong();
		String B = sc.next(); // 文字列で受け取る
		sc.close();
		BigDecimal a = new BigDecimal(A);
		BigDecimal b = new BigDecimal(B);
		prtln(a.multiply(b).toBigInteger());
	}

	public static <T> void prtln(T t) { System.out.println(t); }
} public class Main {

	public static void main(final String[] args) {
		Scanner sc = new Scanner(System.in);
		long A = sc.nextLong();
		String B = sc.next(); // 文字列で受け取る
		sc.close();
		BigDecimal a = new BigDecimal(A);
		BigDecimal b = new BigDecimal(B);
		prtln(a.multiply(b).toBigInteger());
	}

	public static <T> void prtln(T t) { System.out.println(t); }
} Main
import java.math.BigDecimal;
import java.util.Scanner;

public class Main {

	public static void main(final String[] args) {
		Scanner sc = new Scanner(System.in);
		long A = sc.nextLong();
		String B = sc.next(); // 文字列で受け取る
		sc.close();
		BigDecimal a = new BigDecimal(A);
		BigDecimal b = new BigDecimal(B);
		prtln(a.multiply(b).toBigInteger());
	}

	public static <T> void prtln(T t) { System.out.println(t); }
}
