import java.math.BigDecimal;
import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		
		long a = stdIn.nextLong();
		double b = stdIn.nextDouble();
		
		
	//	System.out.println((long)Math.floor(a*b));
		
		
		BigDecimal bd1 = BigDecimal.valueOf(a);
		BigDecimal bd2 = BigDecimal.valueOf(b);
		
		BigDecimal ans = bd1.multiply(bd2).setScale(0,BigDecimal.ROUND_DOWN);
		
		System.out.println(ans);
		
		
		
		
	}

} import java.math.BigDecimal; BigDecimal java.math import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		
		long a = stdIn.nextLong();
		double b = stdIn.nextDouble();
		
		
	//	System.out.println((long)Math.floor(a*b));
		
		
		BigDecimal bd1 = BigDecimal.valueOf(a);
		BigDecimal bd2 = BigDecimal.valueOf(b);
		
		BigDecimal ans = bd1.multiply(bd2).setScale(0,BigDecimal.ROUND_DOWN);
		
		System.out.println(ans);
		
		
		
		
	}

} Main public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		
		long a = stdIn.nextLong();
		double b = stdIn.nextDouble();
		
		
	//	System.out.println((long)Math.floor(a*b));
		
		
		BigDecimal bd1 = BigDecimal.valueOf(a);
		BigDecimal bd2 = BigDecimal.valueOf(b);
		
		BigDecimal ans = bd1.multiply(bd2).setScale(0,BigDecimal.ROUND_DOWN);
		
		System.out.println(ans);
		
		
		
		
	} main {
		Scanner stdIn = new Scanner(System.in);
		
		long a = stdIn.nextLong();
		double b = stdIn.nextDouble();
		
		
	//	System.out.println((long)Math.floor(a*b));
		
		
		BigDecimal bd1 = BigDecimal.valueOf(a);
		BigDecimal bd2 = BigDecimal.valueOf(b);
		
		BigDecimal ans = bd1.multiply(bd2).setScale(0,BigDecimal.ROUND_DOWN);
		
		System.out.println(ans);
		
		
		
		
	} Scanner stdIn = new Scanner(System.in); stdIn new Scanner(System.in) long a = stdIn.nextLong(); a stdIn.nextLong() stdIn.nextLong stdIn double b = stdIn.nextDouble(); b stdIn.nextDouble() stdIn.nextDouble stdIn BigDecimal bd1 = BigDecimal.valueOf(a); bd1 BigDecimal.valueOf(a) BigDecimal.valueOf BigDecimal a BigDecimal bd2 = BigDecimal.valueOf(b); bd2 BigDecimal.valueOf(b) BigDecimal.valueOf BigDecimal b BigDecimal ans = bd1.multiply(bd2).setScale(0,BigDecimal.ROUND_DOWN); ans bd1.multiply(bd2).setScale(0,BigDecimal.ROUND_DOWN) bd1.multiply(bd2).setScale bd1.multiply(bd2) bd1.multiply bd1 bd2 0 BigDecimal.ROUND_DOWN BigDecimal BigDecimal.ROUND_DOWN System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {

	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		
		long a = stdIn.nextLong();
		double b = stdIn.nextDouble();
		
		
	//	System.out.println((long)Math.floor(a*b));
		
		
		BigDecimal bd1 = BigDecimal.valueOf(a);
		BigDecimal bd2 = BigDecimal.valueOf(b);
		
		BigDecimal ans = bd1.multiply(bd2).setScale(0,BigDecimal.ROUND_DOWN);
		
		System.out.println(ans);
		
		
		
		
	}

} public class Main {

	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		
		long a = stdIn.nextLong();
		double b = stdIn.nextDouble();
		
		
	//	System.out.println((long)Math.floor(a*b));
		
		
		BigDecimal bd1 = BigDecimal.valueOf(a);
		BigDecimal bd2 = BigDecimal.valueOf(b);
		
		BigDecimal ans = bd1.multiply(bd2).setScale(0,BigDecimal.ROUND_DOWN);
		
		System.out.println(ans);
		
		
		
		
	}

} Main
import java.math.BigDecimal;
import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		
		long a = stdIn.nextLong();
		double b = stdIn.nextDouble();
		
		
	//	System.out.println((long)Math.floor(a*b));
		
		
		BigDecimal bd1 = BigDecimal.valueOf(a);
		BigDecimal bd2 = BigDecimal.valueOf(b);
		
		BigDecimal ans = bd1.multiply(bd2).setScale(0,BigDecimal.ROUND_DOWN);
		
		System.out.println(ans);
		
		
		
		
	}

}
